[Treatment of colorectal cancer]

The large majority of colorectal cancers are well or moderately differentiated adenocarcinomas. Their biological behavior is not as malignant as that of stomach cancer, with a tendency of slow growth and limited spread. Surgery is therefore the first choice for management of these cancers even in cases where complete removal of the tumor is not expected, surgery is useful for the prolongation or improvement of the quality of life. However, the correct choice of operation for such cases is very important. The extent of resection and dissection must be decided based upon the degree of cancer spread. Both must be sufficient, but not excessive. In cases in the early stage where cancerous growth has not spread beyond the submucosal layer, local or segmental excision may be a good enough treatment. On the other hand, for far advanced rectal cancer involving adjacent organs, combined resection and pelvic evisceration is curatively effective. Several pathological findings of resected specimens influencing prognosis were investigated in the present study. In cases which appeared to be diffuse infiltrative spreading type in macroscopic appearance or poorly differentiated, undifferentiated, or mucinous types of cancer in their histological features, survival rates were low. However, these were uncommon and over half of them were much too far advanced to receive curative resection. Irradiation combined with hyperthermia or heavy chemotherapy were applied, but were mostly ineffective. For these uncommon types of cases as well as far advanced cases, we have no effective treatment other than surgery at this time.