ANALYSIS OF REGIONAL LYMPH-NODE METASTASES FROM RECTAL-CARCINOMA BY THE CLEARING METHOD - JUSTIFICATION OF THE USE OF SIGMOID COLON IN J-POUCH CONSTRUCTION AFTER LOW ANTERIOR RESECTION

PURPOSE: It has been reported that functional outcome following low an terior resection of rectal cancer is improved by construction of a col onic J-pouch compared with straight anastomosis. Hence, we tried to ju stify use of the sigmoid colon in the construction of a J-pouch by the analysis of regional lymph node metastases. METHODS: A total of 182 p atients underwent resection for rectal cancer. Node metastases were ex amined by the clearing method. According to Japanese General Rules for Clinical and Pathological Studies on Cancer of the Colon, Rectum and Anus (JGR), nodes were classified into the perirectal nodes (PR-N), pe ricolic nodes (PC-N), central intermediate nodes (C-IM-N), central mai n nodes (C-M-N), lateral intermediate nodes (L-IM-N), and lateral main nodes (L-M-N). RESULTS: Metastatic rate (number of patients with node metastases/total number of patients) of PR-N was 57.1 percent. Metast atic rate of C-IM-N was 18.7 percent and that of C-M-N was 7.1 percent . Metastatic rates of L-LM-N and L-M-N were 8.8 and 3.3 percent, respe ctively, and both were highest in the case of lower rectal cancer. Met astatic rate of PC-N was only 1.1 percent. The number of cases without node metastases (n(-) cases) was 78, that with only PR-N metastases ( PR-N cases) was 63, that with intermediate but not main node metastase s (IM-N cases) was 29, and that with main node metastases (M-N cases) was 12. Five-year survival rate after curative resection was 88.5 perc ent for n(-) cases, 70.9 percent for PR-N cases, 65.9 percent for IM-N cases, and 41.7 percent for M-N cases. CONCLUSIONS: In low anterior r esection, high ligation of the inferior mesenteric artery and dissecti on of C-M-N, C-IM-N and PR-N are necessary, with the addition of the L -IM-N and L-M-N in the case of lower rectal cancer. Resection of sigmo id colon is not required, and therefore, a J-pouch can be constructed using the sigmoid colon. Nodal classification according to the JGR was predictive of case distribution and five-year survival rate.