Adjuvant radiation therapy for colon cancer

Post-operative radiation therapy has been used in selected patients with colon cancer. In contrast with rectal cancer, the primary failure pattern in colon cancer is abdominal. Local failure does occur, but is less frequent and more difficult to detect. Retrospective data suggest a benefit from local/regional radiation therapy on local control and disease-free survival in subsets of patients compared to historical controls. An ongoing phase III intergroup trial (INT 0130) will determine if local/regional radiation therapy improves the results of chemotherapy in subsets of patients with high-risk colon cancer. In general, the results of whole abdominal radiation plus 5-fluorouracil (5-FU) have been disappointing. However, the more recent data from the Southwest Oncology Group pilot trial are encouraging. In contrast to rectal cancer, where adjuvant chemotherapy plus radiation therapy is standard treatment in high-risk patients, the use of radiation therapy (either local/regional or whole abdomen) in colon cancer remains investigational.