NOVEMBER
The American
Journal
1979
of Surgery VOLUME NUMBER
138 5
EDITORIAL
Polyps and Cancer of the Colon
Claude E. Welch, MD, Boston, Massachusetts
The colonoscope has proved to be an invaluable tool that has led to important advances in the diagnosis and treatment of cancer of the colon. However, the additional information that it has provided to elucidate the polyp-cancer relationship is equally important. Does cancer arise from polyps, or does it begin de novo from the colonic mucosa? For many years supporters of both points of view engaged in verbal sparring that dented personal friendships and at times almost reached the point of physical encounters. Although the echoes of these battles have diminished, it is interesting to recall the historical background of the argument. Colonic and rectal polyps were relatively rare entities approximately 40 years ago. Thereafter the numerous reports that appeared on the subject stressed the probability that cancer arose from polyps; however, essentially all of the evidence that was obtained was circumstantial. In 1958 Spratt et al [I] heeded the queries of a medical student and made a thorough investigation of the problem. They cast serious doubt on any causal relationship. They were applauded by some eminent pathologists who agreed, and such pejorative terms as “polyp slayers” appeared in print. Not unnaturally, this aroused considerable resentment among those who took an opposite point of view. From the Massachusetts General Hospital, Boston, Massachusetts. Reprint requests should be addressed to Claude E. Welch, MD, Suite 1104, Warren Building, 275 Charles Street, Boston, Massachusetts 02114.
Volume 138, November 1979
However, the evidence that cancers usually arise from polyps remained sketchy. Proctologists pointed out the rarity of small cancers and the frequency of benign polyps of the rectum. A few pioneer studies such as that by Gilbertsen [2] indicated that in patients who had had polyps removed from the rectum, many fewer and also less invasive cancers of the rectum developed in future years than in control subjects. However, the lurking suspicion remained that something might be going on in the upper recesses of the colon and that observations on rectal polyps might be negated by further discoveries. However, the colonoscope has erased all of these doubts. Observers who have made complete observations of the colon have proved that the small cancer is a great rarity and that an increase in the size of polyps, regardless of their histologic features, is accompanied by an increase in the number that contain cancer. Data from many institutions parallel those obtained by Lahiry and Hedberg [3] at the Massachusetts General Hospital. For example, in a series of 2,100 polypectomies reported by Hedberg, only 1 cancer was observed in 900 polypoid lesions that were less than 1 cm in diameter. The proportion increased steadily to a 25 per cent incidence of cancerous lesions when the head of the polyp was over 3 cm in diameter. Ultimately, according to present estimates, about 4 per cent of all persons will develop cancer of the colorectum, and thus if cancers appeared de novo, colonoscopy should have demonstrated many more early cancers.
625
Grounds for controversy, however, are not entirely eliminated. Some pathologists maintain that all along they were not talking about all types of polyps but were restricting their remarks to the simple or tubular adenomas and that they doubted the transition of them into cancer. In addition, Fenoglio and Lane [4] have identified a group of “hyperplastic polyps” and consider the great bulk of small polypoid lesions (those about 0.5 cm in diameter) to be of this type, with no malignant potential whatsoever. No pathologist, on the other hand, doubts the frequency of cancer in villous adenomas, nor denies the fact that about 20 to 25 per cent of polypoid lesions are of that type. Ross and Ferrara [5] pointed out that villous patterns could be found on careful study in nearly half of purportedly tubular adenomas. This observation led to the reclassification of polypoid lesions and defined another important class known either as villoglandular polyps or papillary adenomas. The final question remains: does the pure, unadulterated tubular adenoma develop into cancer? Here it must be admitted that observations differ. In our series of lesions removed at the Massachusetts General Hospital by the colonoscope, the incidence of cancer in simple tubular adenomas was less than 1 per cent. This incidence is distinctly lower than the (estimates of Morson [6], who believes that 5 per cent of these lesions ultimately develop malignant change, and of Wolff and Shinya [7], who estimate that approximately 2 to 3 per cent become malignant. Pascal [8], as well as Morson and Bussey [9], have demonstrated changes in single crypts that indicate to them the transition of tubular adenomas directly to cancer. From a practical point of view, however, the histologic character of a polypoid lesion is completely indeterminate until the pathologist has had a chance to carefully study the entire specimen. Since the colonoscope has demonstrated the extreme rarity of small cancers of the colon and the great frequency of small benign polypoid lesions, the presumption seems inescapable that cancer usually
626
develops from a polyp and not de novo. Further observations will be necessary to determine whether the simple tubular adenoma or only those that develop a villous component have a significant cancerous potential. It seems that the removal of all polypoid lesions of the colorectum could solve most of the problems of cancer of the colon. To date, no noninvasive diagnostic technique has been devised by which small lesions can be discovered, and thus the colonoscope, in combination with the barium enema, is our main hope. With colonoscopes and colonoscopists proliferating year by year, the main obstacles that remain are the occasional complications from the procedure and its expense. These objections are formidable enough, however, to restrict the use of colonoscopy to those patients known to be at increased risk, such as those who have had symptoms, who have had previous cancer or polyps, or who have close relatives with these diseases.
References 1. Spratt JS Jr, Ackerman LV, Moyer CA: Relationship of polyps of colon to colonic cancer. Ann Surg 148: 682, 1958. 2. Gilbertsen VA: Proctosigmoidoscopy and polypectomy in reducing the incidence of rectal cancer. Cancer 34 (Suppl): 936, 1974. 3. Lahiry SK, Hedberg SE: Fiberoptic colonoscopy and polypectomy. Complications and management. Presented at meeting of the American Society for Gastrointestinal Endoscopy, Las Vegas, May 4, 1978. 4. Fenoglio CM, Lane N: The anatomic presursor of colorectal carcinoma. JAMA 231: 640, 1974. 5. Ross ST, Ferrara L: Villous tumors of the large bowel. Presented at meeting of the American Proctological Society, Philadelphia, May 10, 1964. Morson BC: The polyp-cancer sequence in the large bowel. Proc R Sot Med 67: 451, 1974. Wolff WI, Shinya H: Definitive treatment of “malignant” polyps of the colon. Ann Surg 182: 516, 1975. Pascal R: Presented at meeting of the New York Cancer Society, New York, February 15, 1979. Morson BC, Bussey HJR: Predisposing causes of intestinal cancer. Curr Rob/ Surg (Feb) 1970.
The American Journal of Surgery
The American
Journal
1979
of Surgery VOLUME NUMBER
138 5
EDITORIAL
Polyps and Cancer of the Colon
Claude E. Welch, MD, Boston, Massachusetts
The colonoscope has proved to be an invaluable tool that has led to important advances in the diagnosis and treatment of cancer of the colon. However, the additional information that it has provided to elucidate the polyp-cancer relationship is equally important. Does cancer arise from polyps, or does it begin de novo from the colonic mucosa? For many years supporters of both points of view engaged in verbal sparring that dented personal friendships and at times almost reached the point of physical encounters. Although the echoes of these battles have diminished, it is interesting to recall the historical background of the argument. Colonic and rectal polyps were relatively rare entities approximately 40 years ago. Thereafter the numerous reports that appeared on the subject stressed the probability that cancer arose from polyps; however, essentially all of the evidence that was obtained was circumstantial. In 1958 Spratt et al [I] heeded the queries of a medical student and made a thorough investigation of the problem. They cast serious doubt on any causal relationship. They were applauded by some eminent pathologists who agreed, and such pejorative terms as “polyp slayers” appeared in print. Not unnaturally, this aroused considerable resentment among those who took an opposite point of view. From the Massachusetts General Hospital, Boston, Massachusetts. Reprint requests should be addressed to Claude E. Welch, MD, Suite 1104, Warren Building, 275 Charles Street, Boston, Massachusetts 02114.
Volume 138, November 1979
However, the evidence that cancers usually arise from polyps remained sketchy. Proctologists pointed out the rarity of small cancers and the frequency of benign polyps of the rectum. A few pioneer studies such as that by Gilbertsen [2] indicated that in patients who had had polyps removed from the rectum, many fewer and also less invasive cancers of the rectum developed in future years than in control subjects. However, the lurking suspicion remained that something might be going on in the upper recesses of the colon and that observations on rectal polyps might be negated by further discoveries. However, the colonoscope has erased all of these doubts. Observers who have made complete observations of the colon have proved that the small cancer is a great rarity and that an increase in the size of polyps, regardless of their histologic features, is accompanied by an increase in the number that contain cancer. Data from many institutions parallel those obtained by Lahiry and Hedberg [3] at the Massachusetts General Hospital. For example, in a series of 2,100 polypectomies reported by Hedberg, only 1 cancer was observed in 900 polypoid lesions that were less than 1 cm in diameter. The proportion increased steadily to a 25 per cent incidence of cancerous lesions when the head of the polyp was over 3 cm in diameter. Ultimately, according to present estimates, about 4 per cent of all persons will develop cancer of the colorectum, and thus if cancers appeared de novo, colonoscopy should have demonstrated many more early cancers.
625
Grounds for controversy, however, are not entirely eliminated. Some pathologists maintain that all along they were not talking about all types of polyps but were restricting their remarks to the simple or tubular adenomas and that they doubted the transition of them into cancer. In addition, Fenoglio and Lane [4] have identified a group of “hyperplastic polyps” and consider the great bulk of small polypoid lesions (those about 0.5 cm in diameter) to be of this type, with no malignant potential whatsoever. No pathologist, on the other hand, doubts the frequency of cancer in villous adenomas, nor denies the fact that about 20 to 25 per cent of polypoid lesions are of that type. Ross and Ferrara [5] pointed out that villous patterns could be found on careful study in nearly half of purportedly tubular adenomas. This observation led to the reclassification of polypoid lesions and defined another important class known either as villoglandular polyps or papillary adenomas. The final question remains: does the pure, unadulterated tubular adenoma develop into cancer? Here it must be admitted that observations differ. In our series of lesions removed at the Massachusetts General Hospital by the colonoscope, the incidence of cancer in simple tubular adenomas was less than 1 per cent. This incidence is distinctly lower than the (estimates of Morson [6], who believes that 5 per cent of these lesions ultimately develop malignant change, and of Wolff and Shinya [7], who estimate that approximately 2 to 3 per cent become malignant. Pascal [8], as well as Morson and Bussey [9], have demonstrated changes in single crypts that indicate to them the transition of tubular adenomas directly to cancer. From a practical point of view, however, the histologic character of a polypoid lesion is completely indeterminate until the pathologist has had a chance to carefully study the entire specimen. Since the colonoscope has demonstrated the extreme rarity of small cancers of the colon and the great frequency of small benign polypoid lesions, the presumption seems inescapable that cancer usually
626
develops from a polyp and not de novo. Further observations will be necessary to determine whether the simple tubular adenoma or only those that develop a villous component have a significant cancerous potential. It seems that the removal of all polypoid lesions of the colorectum could solve most of the problems of cancer of the colon. To date, no noninvasive diagnostic technique has been devised by which small lesions can be discovered, and thus the colonoscope, in combination with the barium enema, is our main hope. With colonoscopes and colonoscopists proliferating year by year, the main obstacles that remain are the occasional complications from the procedure and its expense. These objections are formidable enough, however, to restrict the use of colonoscopy to those patients known to be at increased risk, such as those who have had symptoms, who have had previous cancer or polyps, or who have close relatives with these diseases.
References 1. Spratt JS Jr, Ackerman LV, Moyer CA: Relationship of polyps of colon to colonic cancer. Ann Surg 148: 682, 1958. 2. Gilbertsen VA: Proctosigmoidoscopy and polypectomy in reducing the incidence of rectal cancer. Cancer 34 (Suppl): 936, 1974. 3. Lahiry SK, Hedberg SE: Fiberoptic colonoscopy and polypectomy. Complications and management. Presented at meeting of the American Society for Gastrointestinal Endoscopy, Las Vegas, May 4, 1978. 4. Fenoglio CM, Lane N: The anatomic presursor of colorectal carcinoma. JAMA 231: 640, 1974. 5. Ross ST, Ferrara L: Villous tumors of the large bowel. Presented at meeting of the American Proctological Society, Philadelphia, May 10, 1964. Morson BC: The polyp-cancer sequence in the large bowel. Proc R Sot Med 67: 451, 1974. Wolff WI, Shinya H: Definitive treatment of “malignant” polyps of the colon. Ann Surg 182: 516, 1975. Pascal R: Presented at meeting of the New York Cancer Society, New York, February 15, 1979. Morson BC, Bussey HJR: Predisposing causes of intestinal cancer. Curr Rob/ Surg (Feb) 1970.
The American Journal of Surgery
