[Lymphatic permeation of colorectal cancer--evaluation as a prognostic factor by prospective studies].

To evaluate lymphatic permeation as a prognostic factor in colorectal cancer, long-term prospective studies were conducted and the following results were obtained. 1) The degree of lymphatic permeation increased as the depth of invasion, lymph node metastasis, and stage advanced. 2) Moderate or marked lymphatic permeation (ly2 or ly3) was observed at a high rate in moderately and poorly differentiated adenocarcinoma. 3) Recurrence was more common in the patients with ly2 or ly3. 4) In stage 2 and 3 patients with slight plus no lymphatic permeation (ly0 or ly1), the seven-year survival rates were 89.8% and 85.6%, respectively. In the ly2 + ly3 group, the rates were 67.1% and 66.1%, respectively and a significant difference was noted. In stage 4, however, there was no significant difference between the two groups. Conclusions were as follows. 1) The degree of lymphatic permeation was considered to be extremely closely related to the progression of cancer, histological type and recurrence. 2) In stage 2 and stage 3, the degree of lymphatic permeation was an important prognostic factor, but in stage 4 it was not. 3) It was shown that lymphatic permeation as classified by the authors was a reliable index for survival rates.