METASTASES FROM CARCINOMA OF THE COLON AND RECTUM DETECTED IN SMALL LYMPH-NODES BY THE CLEARING METHOD

study of regional lymph node metastases was performed using the cleari ng method in 322 patients with carcinoma of the colon and rectum (140 with carcinoma of the colon and 182 with carcinoma of the rectum) who had undergone surgical resection. The mean number of nodes examined pe r patient was 76.4 and the metastatic rate (patients with metastases d ivided by the total of patients) was 61.4 percent, with a metastatic i ncidence (nodes with metastases divided by the total of examined nodes ) of 6.4 percent for carcinoma of the colon using the clearing method. For carcinoma of the rectum, the mean number of nodes examined was 73 .7 with a metastatic rate of 57.1 percent and a metastatic incidence o f 7.1 percent. In contrast, node analysis by the conventional manual m ethod resulted in a mean of 18.1 nodes being examined, with a metastat ic rate and incidence of 42.1 and 12.8 percent, respectively, for carc inoma of the colon. Manual examination of lymph nodes in carcinoma of the rectum resulted in a mean of 21.2 nodes being examined, with a met astatic rate and incidence of 50.0 and 16.8 percent, respectively. Com pared with the manual method, the clearing method provided a greater n umber of nodes, a higher metastatic rate and a lower metastatic incide nce. These differences may be explained by the detection of metastatic regional nodes smaller than 4 millimeters in maximum diameter by the clearing method. By TNM classification there were more pN3 than pN2 le sions. The five year survival rate after curative resection was 78.5 p ercent for pN1 lesions, 45.7 percent for pN2 lesions and 45.4 percent for pN3 lesions for carcinoma of the colon and 72.7 percent for pN1 le sions, 75.0 percent for pN2 and 53.9 percent for pN3 lesions for carci noma of the rectum. There was no significant survival difference betwe en the patients with pN1, pN2 and pN3 carcinomas. The presence of regi onal nodes metastases should be examined in detail. Therapies and prog nosis of carcinoma of the colon and rectum should be discussed based o n accurate staging.