A clinicopathological investigation of "tumor nodules" in colorectal cancer

Tumor nodules (tn) have been histologically identified within the fatty tissue or the detached fatty tissue around dissected lymph nodes, or else picked up as lymph nodes from resected specimens with no lymph node components. The TNM classification of malignant tumors provides a description of how to deal with tn, but there has so far been no description within the Japanese classification of colorectal carcinoma. The aim of this study was to determine whether we should regard tn as metastatic lymph nodes from the viewpoint of prognosis. A total of 544 patients who underwent a resection of colorectal adenocarcinoma between 1985 and 1995 were reviewed. Tumor nodules were found in 54 (17.6%) of 307 colon cancer patients, and in 41 (17.3%) of 237 rectal cancer patients. We classified the curability A patients into four groups for both colon and rectal cancer; positive lymph nodes with tn (Group A), negative lymph nodes with tn (Group B), positive lymph nodes without tn (Group C), and negative lymph nodes without tn (Group D). The prognosis was not significantly different between Groups A, B, and C, but it was significantly different between Group D and Groups A, B, and C (P < 0.01) in both the colon and the rectum. From the viewpoint of prognosis, it thus appears justifiable to regard tn as lymph node metastasis.