Seminars in Surgical Oncology 7:157-161 (1991)
Excision of Pulmonary Metastasis of Colorectal Cancer KEVIN D. MURRAY, MD From the Division of Cardiothoracic Surgery, Department of Surgery, Ohio State University, Columbus
Metastasis of colorectal cancer to the lung is a frequent occurrence. Resection of pulmonary metastasis provides the only effective treatment. The initial detection of disease is usually with a chest radiograph. A CAT scan determines the number of lesions, resectability and other metastatic disease. Candidates for surgical excision are those patients with completely resectable singular, multiple, and bilateral metastasis, and those with metachronous liver lesions excised for cure. Exposure of unilateral disease is via a thoracotomy and of bilateral disease via a sternotomy. Metastatic lesions are removed by wedge resection with conservation of lung tissue. Postoperative recovery is usually rapid with low morbidity and mortality. Long-term success for these resections remains controversial. KEY WORDS: wedge resection thoracotomy, median sternotomy, lung
INTRODUCTION
large bowel metastasis show approximately 25% of paColorectal carcinoma is a common malignancy with tients to be alive and disease free at 5 years [lo]. A more than 145,000 new cases diagnosed each year [I]. significant portion of patients eventually demonstrate Metastasis to the lung is a frequent finding after curative pulmonary metastases [9,10]. This extraabdominal abdominal operations [2]. The use of chemotherapy has spread may be present and undetected or develop followbeen ineffective in controlling pulmonary metastasis. ing hepatic resection. The cascade hypothesis of metastaSurgical excision of colorectal lung metastasis was first sis proposes that the first site of colon cancer spread is to described in 1944 [ 3 ] .Since that time great controversy the liver [El. These metastatic deposits then seed the has raged regarding the effectiveness of this treatment pulmonary bed which in turn spreads the malignancy to additional organs. and which patients receive maximum benefit [2,4-6]. This data has been used to determine our selection of The incidence of lung metastasis following a curative surgical patients at the Ohio State University with metoperation for colorectal cancer is approximately 1576, astatic colorectal cancer to the lungs. Patients who demwith the majority (80%) being multiple [7]. Rectal canonstrate pulmonary metastases (either solitary or multicers tend to metastasize more frequently to the lung than ple) that are completely resectable and who have either colon cancers [8]. This is explained by their bypassing no evidence of other metastatic disease or hepatic methe portal venous drainage into the liver. There are conare surgically resected for cure constitute tastases that flicting results regarding the long-term success of surgiour treatment group. cal resection for solitary vs. multiple pulmonary metastaSeveral basic principles hold true for surgical resection sis [2,5,6]. Other features of metastatic colorectal lesions of pulmonary colorectal metastasis: control of the priin the lung-size, location, disease-free interval, colon mary cancer; control of hepatic metastasis; complete recancer stage, sex, and age-appear to have little or no sectability of the lung metastasis; satisfactory pulmonary influence on long-term survival [6]. reserve following chest surgery; and no concomitant disColorectal cancer will frequently metastasize to the liver with the finding of isolated lesions. The development of safe hepatic resections to remove metastatic nodAddress reprint requests to Kevin D. Murray, M.D., Division of Carules has been a major advance in the treatment of this diothoracic Surgery, Department of Surgery, Ohio State University, disease 191. The long-term results of hepatic resection of Columbus, OH 43210. 0 1991 Wiley-Liss, Inc.
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ease that makes surgery hazardous or compromises longterm success. Adherence to these principles will allow proper screening and selection of most patient with this disease process for removal of lung lesions. This operative approach to lung metastasis for colorectal malignancy is undoubtedly controversial. It requires good clinical judgment and careful follow-up to determine surgical success and long-term survival.
SELECTION OF PATIENTS Detection of Pulmonary Metastases
tory should include exercise tolerance, dyspnea (either at rest or with exertion), concomitant lung disease, tobacco use, and other respiratory symptoms. These historical factors can be useful in determining the patient’s ability to tolerate pulmonary surgery. The chest radiograph and CAT scan will disclose any concurrent thoracic disease. Pulmonary function tests are the key determinant for evaluating lung reserve following surgery. The forced expiratory volume at I second (FEV- 1 ) is used to predict the patient’s ability to tolerate pulmonary resection. If the FEV-1 is predicted to be less than 0.8 liters following the lung resection a quantitative ventilation-perfusion scan is used to better estimate pulmonary reserve. This scan determines the contribution of each lobe to ventilation and perfusion. The anticipated volume and location of resected lung tissue can be correlated with this scan to determine the patient’s residual postoperative pulmonary function. Undoubtedly, the estimation of resected lung volume is difficult when nonanatomic pulmonary resections (i .e., wedge resections) are performed by the surgeon. Despite this limitation, we have found this evaluation effective and useful in selecting patients. Room air arterial blood gas analysis assists in predicting ventilatory reserve. An elevated pC0, generates the most concern for overall ventilatory capacity and requires correlation with pulmonary function tests and the patient’s respiratory symptoms with exercise.
The vast majority of patients found with metastatic colon cancer in the lung are discovered by routine chest radiography [ 1 11. The incidence of colon metastasis to the lung is sufficiently high, making routine monitoring of the chest an integral part of any metastatic surveillance protocol for patients with resected colorectal cancer [ 121. A chest radiograph every 3-4 months provides adequate screening for this disease. Carcinoembryonic antigen (CEA) levels are not reliable as a method to detect pulmonary metastases. Several reports have conflicting results regarding the sensitivity of this test as a screening tool for colorectal cancer spread to the lung (12,131. A chest CAT scan provides more detail of the lung lesion(s). This test is obtained following the discovery of an abnormal chest radiograph or when CEA levels are elevated with no identifiable site of recurrence. The chest CAT scan evaluates for other metastatic disease in the COLON lungs, liver, adrenal glands, and lymph nodes. Magnetic It is imperative to evaluate the site of the patient’s resonance imagining (MRI) has not been found useful for primary cancer. Colonoscopy provides the most accurate either screening of this disease or improved detection of and valuable preoperative screening for anastomotic repulmonary metastases not identified by CAT scans [ 131. currence. Additionally, a careful history and physical examination with a rectal examination and testing of PREOPERATIVE EVALUATION stool for occult blood remains important. An abdominal The patient presenting with a lung mass(es>thought to and pelvic CAT scan within 1 month of surgery is necbe a possible metastasis requires an extensive preopera- essary to screen for intraabdominal metastases. tive evaluation. The vast majority of these patients do not have histologic confirmation of their lung lesion. Their METASTATIC SCREENING preoperative work-up must include data that allows the Before any serum tests or imaging studies are ordered, surgeon to know what extent of lung resection the patient a meticulous history and physical examination remains will tolerate in the event the lesion requires a lobectomy the cornerstone of the patient’s evaluation. A change in or pneumonectomy . Failure to have this information the patient’s overall well-being, weight loss, palpable places the patient at risk for a crippling lung operation or adenopathy, bone pain, alteration in mental status, and the need for a second operation. Also, a careful search other pertinent findings directs the selection of approprifor any metastatic disease is necessary to avoid an unate tests. necessary pulmonary resection. Routine screening includes alkaline phosphatase, serum liver function tests, prothrombin time, and serum PULMONARY hemoglobin. Chest and abdominal CAT scans are reThese patients rarely have any respiratory symptoms quired to evaluate for lesions in the liver, adrenal glands, secondary to their lung masses. The majority of lesions lymph nodes, and other high probability areas for metaare peripheral and do not involve the airways. The his- static disease. Brain CAT Scans and bone
Scans are ob-
Lung Metastasis From Colorectal Cancer
tained only when symptoms or serum tests indicate problems in these organs.
ANESTHESIA Prior to the induction of anesthesia, an epidural catheter is placed for postoperative pain management. A catheter is placed in the radial artery for blood pressure monitoring and blood gas analysis. The arterial line is used for all sternotomy incisions and for any patient who has a history of cardiovascular or pulmonary disease. A double lumen endotracheal tube is used for intubation. Proper positioning is verified by auscultation and/or fiberoptic bronchoscopy before the patient is positioned on the operating table. This double lumen endotracheal tube is not a luxury but a necessity. Only with complete deflation of the lung can a thorough and accurate examination detect all metastatic disease. Careful observation is necessary during the deflation of the operated lung to ensure proper ventilation by the opposite lung. The use of continuous positive pressure on the expanded lung often obviates any hypoxemia. A pulse oximeter with or without arterial blood gas analysis indicates the success of one lung ventilation. Extubation is routinely achieved at the end of the operation. If this is not possible because of an extensive pulmonary resection, poor ventilatory dynamics, or prolonged anesthesia effect, a single lumen endotracheal tube is inserted for continued ventilatory support. OPERATIVE APPROACH A thoracotomy incision is used to approach unilateral lung lesion(s). The histologic etiology of the lung mass is generally not known prior to the operation. Although most patients have disease that is highly suspicious for metastatic cancer in the lung, until this is proven, the surgeon must be prepared for all eventualities when the patient arrives in the operating room. Metastatic and benign lesions usually require only a wedge resection while primary lung cancers are removed using a lobectomy or pneumonectomy plus mediastinal lymph node dissection. Thorough preoperative testing will permit the surgeon to perform the appropriate operation without harming the patient or compromising the removal of the pathology. Routine flexible bronchoscopy is not performed unless there is central positioning of any mass(es) or the patient has symptoms (i.e., cough, hemoptysis, etc.) that indicates endobronchial spread of the disease. A limited lateral thoracotomy is the initial incision. The skin opening extends approximately 12 cm horizontally, one finger breadth inferior to the angle of the scapula. Placement of this linear incision allows extension to a standard posterolateral thoracotomy should further exposure be necessary. The serratus anterior muscle is mo-
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bilized and retracted without division. The fifth intercostal space for mid or superior lesions or the sixth intercostal space for mid or lower lesions is entered without excising any segment of rib. The division of intercostal muscles extends well beyond the skin opening. This mobilization of the intercostal space facilitates exposure. The rib spreader is gently opened with great care to avoid breaking any ribs. The lung is deflated and manual exploration is undertaken to determine the extent of parenchymal disease, mediastinal disease or other palpable lesions. The lung lesion(s) is(are) removed using automatic staples with great care taken to provide approximately a 1-2 cm margin of normal tissue. The lesions can be removed in a "V"-shaped wedge resection. Frequently, we have found the more effective method is to grasp the lesion with a non-crushing clamp, elevate it from the underlying lung, and apply the automatic stapler beneath the clamp. Hemostasis is assured by inspection of the staple line. The resected lung tissue is immediately examined to insure the presence of the intended mass for removal. It is imperative that all palpable lesions be removed, no matter their size or consistency. Any residual disease erases the therapeutic efficacy of this procedure. A counterbalance to the need for complete resection is the conservation of lung tissue. A thorough knowledge of the patient's pulmonary reserve permits a thorough resection without making the patient a respiratory cripple. Frozen section microscopic analysis of each excised mass is used to provide the histologic diagnosis. This is important since the pathology of multiple lesions may not be uniform. The finding of metastatic colon cancer or benign disease indicates the end of the operative procedure when all lesions are removed by wedge resection. A single chest tube is placed, the lung is re-inflated, and the chest wall tissues are closed in a standard fashion. If the excised specimen shows a histologic appearance consistent with primary lung cancer then a more extensive resection is warranted for appropriate treatment. Any borderline pathology that has the potential for nonmetastatic disease should be treated as a malignancy originating in the lung. The thoracotomy incision is enlarged and a standard lobectomy or pneumonectomy, with mediastinal lymph node dissection, is performed as the most effective procedure. Bilateral masses necessitate the performance of a median sternotomy incision. This provides access to both lungs. Sequential deflation of each lung with wedge resection of all nodules completes this procedure. Division of the inferior pulmonary ligaments enhances exposure of each lung. The left lower lobe is the most difficult area to examine and to resect nodules. Displacement of this lobe into the operative field interferes with ventricular
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filling and often compromises the systemic blood pressure. The standard use of an arterial catheter to monitor systemic pressure has made extensive resections safer. Individual chest tubes are placed in each pleural space.
UNUSUAL OPERATIVE PROBLEMS The removal of a solitary pulmonary metastatic lesion or several well-defined masses is generally considered a technically simple procedure. The unexpected findings of undetected multiple metastatic nodules. unusual location of lesions, unsuspected pathology. and other problems can make the operative procedure more complex. The finding of multiple pulmonary nodules not present on preoperative imaging poses several problems. It is conceivable that more than one pathologic process exists simultaneously amongst these nodules. Excision of the largest lesion and all additional lesions, regardless of size, consistency, or other gross findings. is necessary to ensure the performance of an appropriate diagnostic and therapeutic operation. The finding of multiple small (1 cm) presents a difficult problem and requires good judgment by the surgeon. If all lesions are removable, providing complete resectability of these metastatic masses, then this would seem a reasonable approach for the surgeon. The concern must be that microscopic or subclinical metastatic disease will remain in the lung. A blind biopsy of normal (according to palpation and inspection), lung parenchyma is done to evaluate for possible widespread microscopic metastatic disease. If frozen section histopathology demonstrates disease in this grossly normal lung then extensive removal of metastatic disease is pointless. The finding of more extensive metastatic disease in the operated lung (not seen on preoperative imaging) arouses suspicion of undetected disease in the contralateral lung. Palpation and biopsy of the opposite lung can be done by dissection across the anterior mediastinum at the level of the pericardium. Although the exposure is limited it does provide a window to examine the other lung and a sampling of tissue for immediate microscopic analysis. The finding of extensive cancer obviates a successful operation. This additional information can be very valuable in determining the extent of disease and the magnitude of surgical resection. Metastatic disease confined to one lobe can warrant the performance of a lobectomy. This decision is based upon its relationship to major pulmonary vessels and airways, the anatomic position of the mass (central vs. peripheral), and the functional capacity of lung tissue remaining following multiple wedge resections from a
single lobe ( i.e. extensive wedge resections leaving negligible tissue). A pneumonectomy is rarely needed and it requires near-absolute certainty that no other active sites of cancer (either in the primary area and other metastatic deposits) exist. A lung with more than a single pulmonary metastasis, evaluated for a pneumonectomy, requires great caution given this operation’s significant morbidity and mortality. The surgeon must know the patient’s pulmonary reserve and his ability to tolerate the loss of one lung. Preoperative testing and imaging should provide reliable information concerning extent of disease and associated pathology. Inspection and palpation of the mediastinum. diaphragm, and chest wall is essential in conjunction with evaluation of the lung. Suspicious, i.e., enlarged or firm mediastinal lymph nodes, are excised and immediately examined histologically. The presence of metastatic colon cancer in these nodes makes a curative resection impossible. The site of removal is marked with clips for possible later external beam radiation. Any palpable mass felt beneath the diaphragm is examined directly through a diaphragmatic incision. The two most common sites of involvement are the liver and adrenal glands. A biopsy specimen is immediately frozen and examined microscopically for evidence of cancer. Metastatic colorectal cancer in these intraabdominal locations makes a curative pulmonary procedure dependent upon the amount of disease in the abdomen and other undetected metastases. We would recommend proceeding with excision of the lung lesion(s) since later abdominal surgery may find these other metastatic sites completely resectable. Either previous pulmonary surgery or pleural disease makes the removal of metastatic lesions in the lung technically challenging. Obliteration of the pleural space requires careful dissection to avoid injury to the lung parenchyma with its associated bleeding and leakage of air. Full mobilization of the lung(s) is necessary in order to properly examine this organ and other thoracic structures. A tear in a major pulmonary artery or vein requires suture repair. Extensive injury may necessitate the performance of a lobectomy or, on rare occasions, cardiopulmonary bypass to permit decompression and repair of a vascular injury. As a routine, we would avoid using any red blood cell-saving suction device given the theoretical potential for reinfusing malignant cells which might facilitate metastatic implants. ~
POSTOPERATIVE CARE Postoperative management of the limited thoracotomy patient is relatively simple. Analgesia is provided by an epidural catheter placed before the induction of anesthesia. This device has been a great asset in the relief of pain. The patient has improved pulmonary function and
Lung Metastasis From Colorectal Cancer
greater compliance with respiratory therapy. This method of analgesia, however, requires routine urinary drainage catheters and decreases the patient’s mobility. Despite these drawbacks, epidural analgesia facilitates postoperative patient care and shortens hospitalization. The epidural catheter is routinely removed 48-72 hours after the completion of the operation. Any evidence of complications from this device, such as headache, fever, or ineffective analgesia, requires prompt removal. The chest tubes remain on suction a minimum of 48 hours. They are then placed on water seal for 12-18 hours. If no air leak is seen and the chest radiograph has no pneumothorax, the tubes are removed. Hospitalization averages 5 days for these procedures.
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CONCLUSIONS Surgical resection for metastatic colorectal cancer to the lung remains the most effective treatment currently available. The extension of operative therapy for this disease beyond those patients with isolated, solitary pulmonary metastasis remains controversial. Long-term results of extensive resection of multiple pulmonary metastases, re-operation for recurrent pulmonary metastases and resection of pulmonary metastases with metachronous liver metastases are not yet available. The operative approach to this disease should be guided by Kocher’s rule: A surgeon is a doctor who can operate and who knows when not to.
ACKNOWLEDGMENTS COMPLICATIONS AND RE-OPERATION I would like to thank Mrs. Renee Lucas for her expert The majority of patients recover rapidly from this tho- preparation of the manuscript. racic procedure. The mortality is low (less than 2%)with a morbidity of less than 5%. Major complications inREFERENCES clude respiratory insufficiency requiring long-term ven1. Holleb A: Cancer clusters cancer statistics. CA 37:2-13, 1987. 2. Pihl E. Hughes ESR. McDermott FT,et al.: Lung recurrence after tilatory support, prolonged air leak from staple lines, curative surgery for colorectal cancer. Dis Colon Rectum 30:417wound infection, and bleeding. 419, 1987. Recurrence of this disease looms as a major problem 3. Blalock A: Recent advances in surgery. N Engl J Med 231:261267, 1944. for these patients. Evidence of pulmonary metastasis within 3 months of surgery generally represents disease 4. Takita H, Edgerton F, Vincent RG, Gutrerrey AC: Surgical management of lung metastasis. In Weiss L, Gilbert HA (eds): “Pulmissed at the time of the initial resection. Later disease monary Metastasis.” Boston: GK Hall and Co, 1978, 243-251. warrants re-evaluation of the primary cancer site and 5 . Morrow CE, Vassilopoulos PP, Grage TB: Surgical resection for metastatic neoplasms of the lung. Cancer 45:2981-2985, 1980. metastatic areas, specifically the liver, to determine new 6. Manse1 JK, Zinsmeister AR, Parrolero PC, Jett JR: Pulmonary evidence of cancer that resulted in additional pulmonary resection of metastatic colorectal adenocarcinoma. Chest 89:109112, 1986. lesions. Re-operation for recurrence has a significant risk for 7. Schulten MF. Heiskell CA, Shields TW: The incidence of pulmonary metastasis from carcinoma of the large intestine. Surg not altering the patient’s long-term survival. Patients Gynecol Obstet 143:727-729, 1976. 8. Weiss L. Grundmann E, Torkorst J , et al.: Haematogenous metwith new lung metastases should not be categorically astatic patterns in colonic carcinoma: An analysis of 1541 necropdenied a second operation; however, a painstaking sies. J Pathol 150:195-203, 1986. search for other metastases and determination of the ex- 9. Fortner JG: Recurrence of colorectal cancer after hepatic resection. Am J Surg 155378-382, 1988. tent of pulmonary disease is an absolute requirement before proceeding with redo surgery. The decision whether 10. Hughes KS, Simon R, Songhorabodi S, et al.: Resection of the liver for colorectal carcinoma metastasis: A multi-institutional to re-operate or not must be made by the surgeon based study of patterns of recurrence. Surgery 2:278-284, 1986. upon data regarding the resectability of the pulmonary 11. Goya T, Miyazawa N , Kondo H, et al.: Surgical resection of pulmonary metastasis from colorectal cancer. Cancer 64.1418disease, the lack of other metastatic lesions, and the pa1421, 1989. tient’s overall condition. The patients and their families 12. Rocklin MS, Sloniski CA, Watne AL: Postoperative surveillance of patients with carcinoma of the colon and rectum. Am Surg must be aware of the risks and benefits of this re56:22-27, 1990. operation, but given their desperate situation, they 13. O’Dwyer PJ, Mojzisik C, McCabe DP, et al.: Reoperation dishould not be expected to make the final decision rected by carcinoembryonic antigen level: The importance of a thorough preoperative evaluation. Am J Surg 155:227-23 I , 1988. whether or not to operate.
Excision of Pulmonary Metastasis of Colorectal Cancer KEVIN D. MURRAY, MD From the Division of Cardiothoracic Surgery, Department of Surgery, Ohio State University, Columbus
Metastasis of colorectal cancer to the lung is a frequent occurrence. Resection of pulmonary metastasis provides the only effective treatment. The initial detection of disease is usually with a chest radiograph. A CAT scan determines the number of lesions, resectability and other metastatic disease. Candidates for surgical excision are those patients with completely resectable singular, multiple, and bilateral metastasis, and those with metachronous liver lesions excised for cure. Exposure of unilateral disease is via a thoracotomy and of bilateral disease via a sternotomy. Metastatic lesions are removed by wedge resection with conservation of lung tissue. Postoperative recovery is usually rapid with low morbidity and mortality. Long-term success for these resections remains controversial. KEY WORDS: wedge resection thoracotomy, median sternotomy, lung
INTRODUCTION
large bowel metastasis show approximately 25% of paColorectal carcinoma is a common malignancy with tients to be alive and disease free at 5 years [lo]. A more than 145,000 new cases diagnosed each year [I]. significant portion of patients eventually demonstrate Metastasis to the lung is a frequent finding after curative pulmonary metastases [9,10]. This extraabdominal abdominal operations [2]. The use of chemotherapy has spread may be present and undetected or develop followbeen ineffective in controlling pulmonary metastasis. ing hepatic resection. The cascade hypothesis of metastaSurgical excision of colorectal lung metastasis was first sis proposes that the first site of colon cancer spread is to described in 1944 [ 3 ] .Since that time great controversy the liver [El. These metastatic deposits then seed the has raged regarding the effectiveness of this treatment pulmonary bed which in turn spreads the malignancy to additional organs. and which patients receive maximum benefit [2,4-6]. This data has been used to determine our selection of The incidence of lung metastasis following a curative surgical patients at the Ohio State University with metoperation for colorectal cancer is approximately 1576, astatic colorectal cancer to the lungs. Patients who demwith the majority (80%) being multiple [7]. Rectal canonstrate pulmonary metastases (either solitary or multicers tend to metastasize more frequently to the lung than ple) that are completely resectable and who have either colon cancers [8]. This is explained by their bypassing no evidence of other metastatic disease or hepatic methe portal venous drainage into the liver. There are conare surgically resected for cure constitute tastases that flicting results regarding the long-term success of surgiour treatment group. cal resection for solitary vs. multiple pulmonary metastaSeveral basic principles hold true for surgical resection sis [2,5,6]. Other features of metastatic colorectal lesions of pulmonary colorectal metastasis: control of the priin the lung-size, location, disease-free interval, colon mary cancer; control of hepatic metastasis; complete recancer stage, sex, and age-appear to have little or no sectability of the lung metastasis; satisfactory pulmonary influence on long-term survival [6]. reserve following chest surgery; and no concomitant disColorectal cancer will frequently metastasize to the liver with the finding of isolated lesions. The development of safe hepatic resections to remove metastatic nodAddress reprint requests to Kevin D. Murray, M.D., Division of Carules has been a major advance in the treatment of this diothoracic Surgery, Department of Surgery, Ohio State University, disease 191. The long-term results of hepatic resection of Columbus, OH 43210. 0 1991 Wiley-Liss, Inc.
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ease that makes surgery hazardous or compromises longterm success. Adherence to these principles will allow proper screening and selection of most patient with this disease process for removal of lung lesions. This operative approach to lung metastasis for colorectal malignancy is undoubtedly controversial. It requires good clinical judgment and careful follow-up to determine surgical success and long-term survival.
SELECTION OF PATIENTS Detection of Pulmonary Metastases
tory should include exercise tolerance, dyspnea (either at rest or with exertion), concomitant lung disease, tobacco use, and other respiratory symptoms. These historical factors can be useful in determining the patient’s ability to tolerate pulmonary surgery. The chest radiograph and CAT scan will disclose any concurrent thoracic disease. Pulmonary function tests are the key determinant for evaluating lung reserve following surgery. The forced expiratory volume at I second (FEV- 1 ) is used to predict the patient’s ability to tolerate pulmonary resection. If the FEV-1 is predicted to be less than 0.8 liters following the lung resection a quantitative ventilation-perfusion scan is used to better estimate pulmonary reserve. This scan determines the contribution of each lobe to ventilation and perfusion. The anticipated volume and location of resected lung tissue can be correlated with this scan to determine the patient’s residual postoperative pulmonary function. Undoubtedly, the estimation of resected lung volume is difficult when nonanatomic pulmonary resections (i .e., wedge resections) are performed by the surgeon. Despite this limitation, we have found this evaluation effective and useful in selecting patients. Room air arterial blood gas analysis assists in predicting ventilatory reserve. An elevated pC0, generates the most concern for overall ventilatory capacity and requires correlation with pulmonary function tests and the patient’s respiratory symptoms with exercise.
The vast majority of patients found with metastatic colon cancer in the lung are discovered by routine chest radiography [ 1 11. The incidence of colon metastasis to the lung is sufficiently high, making routine monitoring of the chest an integral part of any metastatic surveillance protocol for patients with resected colorectal cancer [ 121. A chest radiograph every 3-4 months provides adequate screening for this disease. Carcinoembryonic antigen (CEA) levels are not reliable as a method to detect pulmonary metastases. Several reports have conflicting results regarding the sensitivity of this test as a screening tool for colorectal cancer spread to the lung (12,131. A chest CAT scan provides more detail of the lung lesion(s). This test is obtained following the discovery of an abnormal chest radiograph or when CEA levels are elevated with no identifiable site of recurrence. The chest CAT scan evaluates for other metastatic disease in the COLON lungs, liver, adrenal glands, and lymph nodes. Magnetic It is imperative to evaluate the site of the patient’s resonance imagining (MRI) has not been found useful for primary cancer. Colonoscopy provides the most accurate either screening of this disease or improved detection of and valuable preoperative screening for anastomotic repulmonary metastases not identified by CAT scans [ 131. currence. Additionally, a careful history and physical examination with a rectal examination and testing of PREOPERATIVE EVALUATION stool for occult blood remains important. An abdominal The patient presenting with a lung mass(es>thought to and pelvic CAT scan within 1 month of surgery is necbe a possible metastasis requires an extensive preopera- essary to screen for intraabdominal metastases. tive evaluation. The vast majority of these patients do not have histologic confirmation of their lung lesion. Their METASTATIC SCREENING preoperative work-up must include data that allows the Before any serum tests or imaging studies are ordered, surgeon to know what extent of lung resection the patient a meticulous history and physical examination remains will tolerate in the event the lesion requires a lobectomy the cornerstone of the patient’s evaluation. A change in or pneumonectomy . Failure to have this information the patient’s overall well-being, weight loss, palpable places the patient at risk for a crippling lung operation or adenopathy, bone pain, alteration in mental status, and the need for a second operation. Also, a careful search other pertinent findings directs the selection of approprifor any metastatic disease is necessary to avoid an unate tests. necessary pulmonary resection. Routine screening includes alkaline phosphatase, serum liver function tests, prothrombin time, and serum PULMONARY hemoglobin. Chest and abdominal CAT scans are reThese patients rarely have any respiratory symptoms quired to evaluate for lesions in the liver, adrenal glands, secondary to their lung masses. The majority of lesions lymph nodes, and other high probability areas for metaare peripheral and do not involve the airways. The his- static disease. Brain CAT Scans and bone
Scans are ob-
Lung Metastasis From Colorectal Cancer
tained only when symptoms or serum tests indicate problems in these organs.
ANESTHESIA Prior to the induction of anesthesia, an epidural catheter is placed for postoperative pain management. A catheter is placed in the radial artery for blood pressure monitoring and blood gas analysis. The arterial line is used for all sternotomy incisions and for any patient who has a history of cardiovascular or pulmonary disease. A double lumen endotracheal tube is used for intubation. Proper positioning is verified by auscultation and/or fiberoptic bronchoscopy before the patient is positioned on the operating table. This double lumen endotracheal tube is not a luxury but a necessity. Only with complete deflation of the lung can a thorough and accurate examination detect all metastatic disease. Careful observation is necessary during the deflation of the operated lung to ensure proper ventilation by the opposite lung. The use of continuous positive pressure on the expanded lung often obviates any hypoxemia. A pulse oximeter with or without arterial blood gas analysis indicates the success of one lung ventilation. Extubation is routinely achieved at the end of the operation. If this is not possible because of an extensive pulmonary resection, poor ventilatory dynamics, or prolonged anesthesia effect, a single lumen endotracheal tube is inserted for continued ventilatory support. OPERATIVE APPROACH A thoracotomy incision is used to approach unilateral lung lesion(s). The histologic etiology of the lung mass is generally not known prior to the operation. Although most patients have disease that is highly suspicious for metastatic cancer in the lung, until this is proven, the surgeon must be prepared for all eventualities when the patient arrives in the operating room. Metastatic and benign lesions usually require only a wedge resection while primary lung cancers are removed using a lobectomy or pneumonectomy plus mediastinal lymph node dissection. Thorough preoperative testing will permit the surgeon to perform the appropriate operation without harming the patient or compromising the removal of the pathology. Routine flexible bronchoscopy is not performed unless there is central positioning of any mass(es) or the patient has symptoms (i.e., cough, hemoptysis, etc.) that indicates endobronchial spread of the disease. A limited lateral thoracotomy is the initial incision. The skin opening extends approximately 12 cm horizontally, one finger breadth inferior to the angle of the scapula. Placement of this linear incision allows extension to a standard posterolateral thoracotomy should further exposure be necessary. The serratus anterior muscle is mo-
159
bilized and retracted without division. The fifth intercostal space for mid or superior lesions or the sixth intercostal space for mid or lower lesions is entered without excising any segment of rib. The division of intercostal muscles extends well beyond the skin opening. This mobilization of the intercostal space facilitates exposure. The rib spreader is gently opened with great care to avoid breaking any ribs. The lung is deflated and manual exploration is undertaken to determine the extent of parenchymal disease, mediastinal disease or other palpable lesions. The lung lesion(s) is(are) removed using automatic staples with great care taken to provide approximately a 1-2 cm margin of normal tissue. The lesions can be removed in a "V"-shaped wedge resection. Frequently, we have found the more effective method is to grasp the lesion with a non-crushing clamp, elevate it from the underlying lung, and apply the automatic stapler beneath the clamp. Hemostasis is assured by inspection of the staple line. The resected lung tissue is immediately examined to insure the presence of the intended mass for removal. It is imperative that all palpable lesions be removed, no matter their size or consistency. Any residual disease erases the therapeutic efficacy of this procedure. A counterbalance to the need for complete resection is the conservation of lung tissue. A thorough knowledge of the patient's pulmonary reserve permits a thorough resection without making the patient a respiratory cripple. Frozen section microscopic analysis of each excised mass is used to provide the histologic diagnosis. This is important since the pathology of multiple lesions may not be uniform. The finding of metastatic colon cancer or benign disease indicates the end of the operative procedure when all lesions are removed by wedge resection. A single chest tube is placed, the lung is re-inflated, and the chest wall tissues are closed in a standard fashion. If the excised specimen shows a histologic appearance consistent with primary lung cancer then a more extensive resection is warranted for appropriate treatment. Any borderline pathology that has the potential for nonmetastatic disease should be treated as a malignancy originating in the lung. The thoracotomy incision is enlarged and a standard lobectomy or pneumonectomy, with mediastinal lymph node dissection, is performed as the most effective procedure. Bilateral masses necessitate the performance of a median sternotomy incision. This provides access to both lungs. Sequential deflation of each lung with wedge resection of all nodules completes this procedure. Division of the inferior pulmonary ligaments enhances exposure of each lung. The left lower lobe is the most difficult area to examine and to resect nodules. Displacement of this lobe into the operative field interferes with ventricular
160
Murray
filling and often compromises the systemic blood pressure. The standard use of an arterial catheter to monitor systemic pressure has made extensive resections safer. Individual chest tubes are placed in each pleural space.
UNUSUAL OPERATIVE PROBLEMS The removal of a solitary pulmonary metastatic lesion or several well-defined masses is generally considered a technically simple procedure. The unexpected findings of undetected multiple metastatic nodules. unusual location of lesions, unsuspected pathology. and other problems can make the operative procedure more complex. The finding of multiple pulmonary nodules not present on preoperative imaging poses several problems. It is conceivable that more than one pathologic process exists simultaneously amongst these nodules. Excision of the largest lesion and all additional lesions, regardless of size, consistency, or other gross findings. is necessary to ensure the performance of an appropriate diagnostic and therapeutic operation. The finding of multiple small (1 cm) presents a difficult problem and requires good judgment by the surgeon. If all lesions are removable, providing complete resectability of these metastatic masses, then this would seem a reasonable approach for the surgeon. The concern must be that microscopic or subclinical metastatic disease will remain in the lung. A blind biopsy of normal (according to palpation and inspection), lung parenchyma is done to evaluate for possible widespread microscopic metastatic disease. If frozen section histopathology demonstrates disease in this grossly normal lung then extensive removal of metastatic disease is pointless. The finding of more extensive metastatic disease in the operated lung (not seen on preoperative imaging) arouses suspicion of undetected disease in the contralateral lung. Palpation and biopsy of the opposite lung can be done by dissection across the anterior mediastinum at the level of the pericardium. Although the exposure is limited it does provide a window to examine the other lung and a sampling of tissue for immediate microscopic analysis. The finding of extensive cancer obviates a successful operation. This additional information can be very valuable in determining the extent of disease and the magnitude of surgical resection. Metastatic disease confined to one lobe can warrant the performance of a lobectomy. This decision is based upon its relationship to major pulmonary vessels and airways, the anatomic position of the mass (central vs. peripheral), and the functional capacity of lung tissue remaining following multiple wedge resections from a
single lobe ( i.e. extensive wedge resections leaving negligible tissue). A pneumonectomy is rarely needed and it requires near-absolute certainty that no other active sites of cancer (either in the primary area and other metastatic deposits) exist. A lung with more than a single pulmonary metastasis, evaluated for a pneumonectomy, requires great caution given this operation’s significant morbidity and mortality. The surgeon must know the patient’s pulmonary reserve and his ability to tolerate the loss of one lung. Preoperative testing and imaging should provide reliable information concerning extent of disease and associated pathology. Inspection and palpation of the mediastinum. diaphragm, and chest wall is essential in conjunction with evaluation of the lung. Suspicious, i.e., enlarged or firm mediastinal lymph nodes, are excised and immediately examined histologically. The presence of metastatic colon cancer in these nodes makes a curative resection impossible. The site of removal is marked with clips for possible later external beam radiation. Any palpable mass felt beneath the diaphragm is examined directly through a diaphragmatic incision. The two most common sites of involvement are the liver and adrenal glands. A biopsy specimen is immediately frozen and examined microscopically for evidence of cancer. Metastatic colorectal cancer in these intraabdominal locations makes a curative pulmonary procedure dependent upon the amount of disease in the abdomen and other undetected metastases. We would recommend proceeding with excision of the lung lesion(s) since later abdominal surgery may find these other metastatic sites completely resectable. Either previous pulmonary surgery or pleural disease makes the removal of metastatic lesions in the lung technically challenging. Obliteration of the pleural space requires careful dissection to avoid injury to the lung parenchyma with its associated bleeding and leakage of air. Full mobilization of the lung(s) is necessary in order to properly examine this organ and other thoracic structures. A tear in a major pulmonary artery or vein requires suture repair. Extensive injury may necessitate the performance of a lobectomy or, on rare occasions, cardiopulmonary bypass to permit decompression and repair of a vascular injury. As a routine, we would avoid using any red blood cell-saving suction device given the theoretical potential for reinfusing malignant cells which might facilitate metastatic implants. ~
POSTOPERATIVE CARE Postoperative management of the limited thoracotomy patient is relatively simple. Analgesia is provided by an epidural catheter placed before the induction of anesthesia. This device has been a great asset in the relief of pain. The patient has improved pulmonary function and
Lung Metastasis From Colorectal Cancer
greater compliance with respiratory therapy. This method of analgesia, however, requires routine urinary drainage catheters and decreases the patient’s mobility. Despite these drawbacks, epidural analgesia facilitates postoperative patient care and shortens hospitalization. The epidural catheter is routinely removed 48-72 hours after the completion of the operation. Any evidence of complications from this device, such as headache, fever, or ineffective analgesia, requires prompt removal. The chest tubes remain on suction a minimum of 48 hours. They are then placed on water seal for 12-18 hours. If no air leak is seen and the chest radiograph has no pneumothorax, the tubes are removed. Hospitalization averages 5 days for these procedures.
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CONCLUSIONS Surgical resection for metastatic colorectal cancer to the lung remains the most effective treatment currently available. The extension of operative therapy for this disease beyond those patients with isolated, solitary pulmonary metastasis remains controversial. Long-term results of extensive resection of multiple pulmonary metastases, re-operation for recurrent pulmonary metastases and resection of pulmonary metastases with metachronous liver metastases are not yet available. The operative approach to this disease should be guided by Kocher’s rule: A surgeon is a doctor who can operate and who knows when not to.
ACKNOWLEDGMENTS COMPLICATIONS AND RE-OPERATION I would like to thank Mrs. Renee Lucas for her expert The majority of patients recover rapidly from this tho- preparation of the manuscript. racic procedure. The mortality is low (less than 2%)with a morbidity of less than 5%. Major complications inREFERENCES clude respiratory insufficiency requiring long-term ven1. Holleb A: Cancer clusters cancer statistics. CA 37:2-13, 1987. 2. Pihl E. Hughes ESR. McDermott FT,et al.: Lung recurrence after tilatory support, prolonged air leak from staple lines, curative surgery for colorectal cancer. Dis Colon Rectum 30:417wound infection, and bleeding. 419, 1987. Recurrence of this disease looms as a major problem 3. Blalock A: Recent advances in surgery. N Engl J Med 231:261267, 1944. for these patients. Evidence of pulmonary metastasis within 3 months of surgery generally represents disease 4. Takita H, Edgerton F, Vincent RG, Gutrerrey AC: Surgical management of lung metastasis. In Weiss L, Gilbert HA (eds): “Pulmissed at the time of the initial resection. Later disease monary Metastasis.” Boston: GK Hall and Co, 1978, 243-251. warrants re-evaluation of the primary cancer site and 5 . Morrow CE, Vassilopoulos PP, Grage TB: Surgical resection for metastatic neoplasms of the lung. Cancer 45:2981-2985, 1980. metastatic areas, specifically the liver, to determine new 6. Manse1 JK, Zinsmeister AR, Parrolero PC, Jett JR: Pulmonary evidence of cancer that resulted in additional pulmonary resection of metastatic colorectal adenocarcinoma. Chest 89:109112, 1986. lesions. Re-operation for recurrence has a significant risk for 7. Schulten MF. Heiskell CA, Shields TW: The incidence of pulmonary metastasis from carcinoma of the large intestine. Surg not altering the patient’s long-term survival. Patients Gynecol Obstet 143:727-729, 1976. 8. Weiss L. Grundmann E, Torkorst J , et al.: Haematogenous metwith new lung metastases should not be categorically astatic patterns in colonic carcinoma: An analysis of 1541 necropdenied a second operation; however, a painstaking sies. J Pathol 150:195-203, 1986. search for other metastases and determination of the ex- 9. Fortner JG: Recurrence of colorectal cancer after hepatic resection. Am J Surg 155378-382, 1988. tent of pulmonary disease is an absolute requirement before proceeding with redo surgery. The decision whether 10. Hughes KS, Simon R, Songhorabodi S, et al.: Resection of the liver for colorectal carcinoma metastasis: A multi-institutional to re-operate or not must be made by the surgeon based study of patterns of recurrence. Surgery 2:278-284, 1986. upon data regarding the resectability of the pulmonary 11. Goya T, Miyazawa N , Kondo H, et al.: Surgical resection of pulmonary metastasis from colorectal cancer. Cancer 64.1418disease, the lack of other metastatic lesions, and the pa1421, 1989. tient’s overall condition. The patients and their families 12. Rocklin MS, Sloniski CA, Watne AL: Postoperative surveillance of patients with carcinoma of the colon and rectum. Am Surg must be aware of the risks and benefits of this re56:22-27, 1990. operation, but given their desperate situation, they 13. O’Dwyer PJ, Mojzisik C, McCabe DP, et al.: Reoperation dishould not be expected to make the final decision rected by carcinoembryonic antigen level: The importance of a thorough preoperative evaluation. Am J Surg 155:227-23 I , 1988. whether or not to operate.
