Adjuvant radiation therapy in colon cancer.

The overall five year survival of patients with colorectal cancer is excellent compared with other major visceral malignancies. This is attributable to effect surgical treatment, yet the death rate per 100,000 population has improved little in recent decades, stimulating a search for adjuvant treatment modalities until a better understanding of etiology and pathogenesis results in prevention of earlier diagnosis. Combination of the known cancerocidal effect of ionizing radiation and surgical excision has been used sporadically for over six decades, but only recently has this combined modality therapy been studied in a scientific manner. Numerous variables such as source of radiation, total tumor dose, dose-time factors, location of portals of treatment, size and shape of radiation fields, and the radiation-surgery sequence are now being studied. Current information leaves little doubt of the effectiveness of this combined modality therapy in selected patients. Controlled clinical trials must continue in order to obtain more solid data, which hopefully will eventually result in substantially improved survival.