Clinicopathologic Studies on Perineural Invasion of Bile Duct Carcinoma
MD. MUKHLESUR RAHMAN BHUIYA, M.B.B.S., YUJI NIMURA, M.D., JUNICHI KAMIYA, M.D., SATOSHI KONDO, M.D., SHINJI FUKATA, M.D., NAOKAZU HAYAKAWA, M.D., and SHIGEHIKO SHIONOYA, M.D.
To elucidate the clinical significance of perineural invasion on bile duct cancer, a clinicopathologic study was performed on 70 resected patients with bile duct carcinoma. The overall incidence of perineural invasion in the resected specimen was 81.4%. There seemed to be no correlation between perineural invasion and site, size of the tumor, and lymph node metastasis. A significant correlation was observed, however, between macroscopic type, microscopic type, depth of invasion, and perineural invasion. Perineural invasion index (PNI) was defined as the ratio between the number of nerve fibers invaded by cancer and the total number of nerve fibers with and without cancer invasion. Perineural invasion index was significantly higher at the center compared with the proximal and distal part of the tumor (p < 0.001). The 5-year survival rate for patients with perineural invasion was significantly lower (p < 0.05) than that for those without perineural invasion (67% versus 32%).
PREADING OF TUMOR through the perineurium and its clinical significance has been described in Li a variety of head and neck,1-6 prostate,6-8 and pancreas9-'3 tumors. Previously, the perineural space was believed to be a part of the lymphatic system.4" 5 Contrary to this, later studies described this space as a separate channel from the lymphatic system and as an independent route of tumor metastasis.68 Many authors have emphasized the nerve dissection together with the tumor resection as a more radical approach to head, neck,' 2"16"17 and pancreas head tumors.9"'0 The perineural spread ofbile duct cancer and its clinical significance, however, remain unclear. No extensive study has been conducted on bile duct cancer. The purpose of this present study is to evaluate the clinical role of perineural invasion in bile duct cancer, especially its influence on the prognosis and the mode of spread of this tumor through the perineurium. Address reprint requests to Md. Mukhlesur Rahman Bhuiya, M.B.B.S., The First Department of Surgery, Nagoya University School of Medicine. 65 Tsurumai-cho, Showa-ku, Nagoya 466, Japan. Accepted for publication October 29, 1991.
344
From the First Department of Surgery, Nagoya University School of Medicine, Nagoya, Japan
Materials and Methods
From January 1979 through September 1990, 94 cases of bile duct carcinoma were resected at the First Department of Surgery, Nagoya University Hospital. This study was conducted on 70 of the 94 resected cases on whom all necessary information was available; the remaining 24 cases were excluded from this study because of a lack of sufficient information. The age ofthe patients ranged from 32 to 82 years (mean, 57 years). Of the 70 patients, 48 (68.5%) were men and 22 (31.5%) were women. In this study, the term carcinoma of the hepatic hilus included lesions arising from the common hepatic duct, right, left, or both hepatic duct and intrahepatic bile duct cancer invading the hepatic hilus. The middle and lower bile duct cancers also were included, and the lesions arising from the papilla of Vater and the gallbladder were excluded from this study. All patients were precisely evaluated preoperatively, and the lesions were resected at the following surgical operations: 1. Bile duct resection only (n = 2) 2. Hepatectomy with bile duct resection (n = 46) 3. Pancreatoduodenectomy (n = 18) 4. Hepatopancreatoduodenectomy'8(n = 4) After operation, the resected specimens were immediately processed first with normal saline and then with a mixture of equal parts of formalin. Resected specimen cholangiography was done for every case. Each then was washed, photographed, described, and then submersed into the formalin solution before further study. The fixed resected specimens were serially sliced in each 5 mm that corresponded with the cuts generated by the recent com-
VOl. 2155. NO. 4
PERINEURAL INVASION OF BILE DUCT CANCER
puted tomography (CT) scan. The blocks were taken from the slices processed through paraffin and the slides were prepared for microscopic study staining with hematoxylin and eosin. The perineural invasion was defined as tumor cells found in the perineural spaces and extending along them. Nerve fiber with or without perineural cancer invasion was calculated at least three places in each part of the tumor, and perineural invasion index (PNI) was calculated from the mean values in each part of the tumor according to the following formula:
FIG. 1. The microscopic features of (a) PNI grade I bile duct cancer show no cancer cells in the perineural space (arrows). Invasion of many perineural spaces by cancer cells (arrowheads) and some of the perineural spaces without cancer invasion (arrows) can be seen in (b) PNI grade II bile duct cancer. Almost all of the perineural spaces are severely involved by cancer cells (arrowheads) in case of (c) PNI grade III bile duct cancer.
345
Number of nerve fiber invaded by tumor PNI - Total number of nerve fibers with and without tumor invasion The PNI was calculated at the proximal end, the center, and the distal end of the tumor, and the grade of perineural invasion was made according to the PNI. Grade I means PNI = 0.00 (this group had no perineural invasion), grade II means PNI < 0.70, and grade III means PNI 2 0.70 (this group had severe perineural invasion) (Fig. 1). Fol-
Ann. Surg. * April 1992 BHUIYA AND OTHERS 346 TABLE 2. Relation Between Gross Type of Lesion low-up information was available for all 70 patients for and Perineural Invasion periods that varied from 9 months to 131 months, the average being 65.5 months. The Kaplan-Meier method Perineural Invasion was used to evaluate the survival rate. The statistical analPositive Negative Gross Type ysis was done by paired and nonpaired Student's t test, generalized Wilcoxon test, and chi square test. 8 (57.2%) 6 (42.8%) Papillary (n = 14)
Results Operative Procedures An operative procedure was selected according to the preoperative precise diagnosis. Curative operation was performed in 53 patients and noncurative resection in 17 patients. In case of bile duct carcinoma of the hepatic hilus, caudate lobe resection was included in all patients together with bile duct or liver resection according to our strategy of treating this carcinoma.'9
Perineural Invasion Index in Bile Duct Cancer To find out the frequency of perineural invasion in bile duct cancer and possible direction of spread of cancer through the perineural space, the PNI was calculated at the proximal, center, and distal part ofthe bile duct cancer (Table 1). This showed the distinct significant differences of PNI between the center of the tumor, and proximal or distal to the tumor (p < 0.001). Conversely, the distal PNI was significantly more than that of the proximal in carcinoma of the hepatic hilus (p < 0.01). There was, however, no significant difference between the proximal and distal site of the tumor in middle and lower bile duct cancer. These findings suggested that the most frequent site of nerve involvement by cancer was around the center ofthe tumor and could be disseminated either proximally or distally through the perineural space, but the distal dissemination was more frequent than proximal (p < 0.01). Perineural Invasion and Location of Primary Tumor Fifty-seven of the total seventy (81.4%) resected cases of bile duct cancer showed perineural invasion. It was
Nodular (n 22) Nodular infiltrating (n = 10) Infiltrating (n = 24) Total (n = 70)
17 (77.2%) 10 (100.0%) 24 (100.0%) 57 (81.4%)
5 (22.8%) 0 (0.0%) 0 (0.0%) 13 (18.6%)
Statistically significant (p < 0.01).
observed in 42 of 52 (80.7%) of the carcinoma of the hepatic hilus, 7 of 8 (87.5%) of the middle bile duct cancer, and 8 of 10 (80%) of the lower bile duct cancer. From these findings, no significant conclusion could be drawn as to the relation between the primary site of tumor and perineural invasion. The relation between the gross macroscopic feature of the lesion and perineural invasion is shown in Table 2. There was a statistically significant relation between the macroscopic type of the tumor and the presence of perineural cancer invasion (p < 0.01).
Correlation Between Perineural Invasion and Histologic Type
Penineural invasion was less frequently observed in papillary adenocarcinoma than in the other histologic types (Table 3). These findings were suggestive of a correlation between the histologic type and perineural invasion. The statistically significant correlation was observed between the papillary and nonpapillary carcinomas (p < 0.05). The relation between the depth of cancer invasion and perineural invasion is shown in Table 4. A distinct significant correlation can be found between the depth of cancer invasion and perineural invasion (p < 0.01). The TABLE 3. Correlation Between Perineural Invasion and Histologic Type
Perineural Invasion TABLE 1. Perineural Invasion Index in Bile Duct Cancer
Histologic Type Location of PNI Calculation
Mean *
±
Hepatic Hilus 0.06 0.37 0.13
Proximal Center Distal
Positive
Negative
Location of Primary Lesion
0.04] *1 ± 0.31 ± 0.09 ±
SD.
p < 0.001.
tp
MD. MUKHLESUR RAHMAN BHUIYA, M.B.B.S., YUJI NIMURA, M.D., JUNICHI KAMIYA, M.D., SATOSHI KONDO, M.D., SHINJI FUKATA, M.D., NAOKAZU HAYAKAWA, M.D., and SHIGEHIKO SHIONOYA, M.D.
To elucidate the clinical significance of perineural invasion on bile duct cancer, a clinicopathologic study was performed on 70 resected patients with bile duct carcinoma. The overall incidence of perineural invasion in the resected specimen was 81.4%. There seemed to be no correlation between perineural invasion and site, size of the tumor, and lymph node metastasis. A significant correlation was observed, however, between macroscopic type, microscopic type, depth of invasion, and perineural invasion. Perineural invasion index (PNI) was defined as the ratio between the number of nerve fibers invaded by cancer and the total number of nerve fibers with and without cancer invasion. Perineural invasion index was significantly higher at the center compared with the proximal and distal part of the tumor (p < 0.001). The 5-year survival rate for patients with perineural invasion was significantly lower (p < 0.05) than that for those without perineural invasion (67% versus 32%).
PREADING OF TUMOR through the perineurium and its clinical significance has been described in Li a variety of head and neck,1-6 prostate,6-8 and pancreas9-'3 tumors. Previously, the perineural space was believed to be a part of the lymphatic system.4" 5 Contrary to this, later studies described this space as a separate channel from the lymphatic system and as an independent route of tumor metastasis.68 Many authors have emphasized the nerve dissection together with the tumor resection as a more radical approach to head, neck,' 2"16"17 and pancreas head tumors.9"'0 The perineural spread ofbile duct cancer and its clinical significance, however, remain unclear. No extensive study has been conducted on bile duct cancer. The purpose of this present study is to evaluate the clinical role of perineural invasion in bile duct cancer, especially its influence on the prognosis and the mode of spread of this tumor through the perineurium. Address reprint requests to Md. Mukhlesur Rahman Bhuiya, M.B.B.S., The First Department of Surgery, Nagoya University School of Medicine. 65 Tsurumai-cho, Showa-ku, Nagoya 466, Japan. Accepted for publication October 29, 1991.
344
From the First Department of Surgery, Nagoya University School of Medicine, Nagoya, Japan
Materials and Methods
From January 1979 through September 1990, 94 cases of bile duct carcinoma were resected at the First Department of Surgery, Nagoya University Hospital. This study was conducted on 70 of the 94 resected cases on whom all necessary information was available; the remaining 24 cases were excluded from this study because of a lack of sufficient information. The age ofthe patients ranged from 32 to 82 years (mean, 57 years). Of the 70 patients, 48 (68.5%) were men and 22 (31.5%) were women. In this study, the term carcinoma of the hepatic hilus included lesions arising from the common hepatic duct, right, left, or both hepatic duct and intrahepatic bile duct cancer invading the hepatic hilus. The middle and lower bile duct cancers also were included, and the lesions arising from the papilla of Vater and the gallbladder were excluded from this study. All patients were precisely evaluated preoperatively, and the lesions were resected at the following surgical operations: 1. Bile duct resection only (n = 2) 2. Hepatectomy with bile duct resection (n = 46) 3. Pancreatoduodenectomy (n = 18) 4. Hepatopancreatoduodenectomy'8(n = 4) After operation, the resected specimens were immediately processed first with normal saline and then with a mixture of equal parts of formalin. Resected specimen cholangiography was done for every case. Each then was washed, photographed, described, and then submersed into the formalin solution before further study. The fixed resected specimens were serially sliced in each 5 mm that corresponded with the cuts generated by the recent com-
VOl. 2155. NO. 4
PERINEURAL INVASION OF BILE DUCT CANCER
puted tomography (CT) scan. The blocks were taken from the slices processed through paraffin and the slides were prepared for microscopic study staining with hematoxylin and eosin. The perineural invasion was defined as tumor cells found in the perineural spaces and extending along them. Nerve fiber with or without perineural cancer invasion was calculated at least three places in each part of the tumor, and perineural invasion index (PNI) was calculated from the mean values in each part of the tumor according to the following formula:
FIG. 1. The microscopic features of (a) PNI grade I bile duct cancer show no cancer cells in the perineural space (arrows). Invasion of many perineural spaces by cancer cells (arrowheads) and some of the perineural spaces without cancer invasion (arrows) can be seen in (b) PNI grade II bile duct cancer. Almost all of the perineural spaces are severely involved by cancer cells (arrowheads) in case of (c) PNI grade III bile duct cancer.
345
Number of nerve fiber invaded by tumor PNI - Total number of nerve fibers with and without tumor invasion The PNI was calculated at the proximal end, the center, and the distal end of the tumor, and the grade of perineural invasion was made according to the PNI. Grade I means PNI = 0.00 (this group had no perineural invasion), grade II means PNI < 0.70, and grade III means PNI 2 0.70 (this group had severe perineural invasion) (Fig. 1). Fol-
Ann. Surg. * April 1992 BHUIYA AND OTHERS 346 TABLE 2. Relation Between Gross Type of Lesion low-up information was available for all 70 patients for and Perineural Invasion periods that varied from 9 months to 131 months, the average being 65.5 months. The Kaplan-Meier method Perineural Invasion was used to evaluate the survival rate. The statistical analPositive Negative Gross Type ysis was done by paired and nonpaired Student's t test, generalized Wilcoxon test, and chi square test. 8 (57.2%) 6 (42.8%) Papillary (n = 14)
Results Operative Procedures An operative procedure was selected according to the preoperative precise diagnosis. Curative operation was performed in 53 patients and noncurative resection in 17 patients. In case of bile duct carcinoma of the hepatic hilus, caudate lobe resection was included in all patients together with bile duct or liver resection according to our strategy of treating this carcinoma.'9
Perineural Invasion Index in Bile Duct Cancer To find out the frequency of perineural invasion in bile duct cancer and possible direction of spread of cancer through the perineural space, the PNI was calculated at the proximal, center, and distal part ofthe bile duct cancer (Table 1). This showed the distinct significant differences of PNI between the center of the tumor, and proximal or distal to the tumor (p < 0.001). Conversely, the distal PNI was significantly more than that of the proximal in carcinoma of the hepatic hilus (p < 0.01). There was, however, no significant difference between the proximal and distal site of the tumor in middle and lower bile duct cancer. These findings suggested that the most frequent site of nerve involvement by cancer was around the center ofthe tumor and could be disseminated either proximally or distally through the perineural space, but the distal dissemination was more frequent than proximal (p < 0.01). Perineural Invasion and Location of Primary Tumor Fifty-seven of the total seventy (81.4%) resected cases of bile duct cancer showed perineural invasion. It was
Nodular (n 22) Nodular infiltrating (n = 10) Infiltrating (n = 24) Total (n = 70)
17 (77.2%) 10 (100.0%) 24 (100.0%) 57 (81.4%)
5 (22.8%) 0 (0.0%) 0 (0.0%) 13 (18.6%)
Statistically significant (p < 0.01).
observed in 42 of 52 (80.7%) of the carcinoma of the hepatic hilus, 7 of 8 (87.5%) of the middle bile duct cancer, and 8 of 10 (80%) of the lower bile duct cancer. From these findings, no significant conclusion could be drawn as to the relation between the primary site of tumor and perineural invasion. The relation between the gross macroscopic feature of the lesion and perineural invasion is shown in Table 2. There was a statistically significant relation between the macroscopic type of the tumor and the presence of perineural cancer invasion (p < 0.01).
Correlation Between Perineural Invasion and Histologic Type
Penineural invasion was less frequently observed in papillary adenocarcinoma than in the other histologic types (Table 3). These findings were suggestive of a correlation between the histologic type and perineural invasion. The statistically significant correlation was observed between the papillary and nonpapillary carcinomas (p < 0.05). The relation between the depth of cancer invasion and perineural invasion is shown in Table 4. A distinct significant correlation can be found between the depth of cancer invasion and perineural invasion (p < 0.01). The TABLE 3. Correlation Between Perineural Invasion and Histologic Type
Perineural Invasion TABLE 1. Perineural Invasion Index in Bile Duct Cancer
Histologic Type Location of PNI Calculation
Mean *
±
Hepatic Hilus 0.06 0.37 0.13
Proximal Center Distal
Positive
Negative
Location of Primary Lesion
0.04] *1 ± 0.31 ± 0.09 ±
SD.
p < 0.001.
tp
