Large-field, external beam irradiation as a surgical adjuvant for node-positive colon carcinoma: an Eastern Cooperative Oncology Group Pilot Study (PA285).

The Eastern Cooperative Oncology Group (ECOG) PA-285 study was designed as a pilot study to evaluate the effect of large-field, external beam abdominal irradiation as an adjuvant treatment for resectable stage C1 to C2 colon cancer. Eligible patients received 45 Gy directed to the tumor bed and periaortic lymph nodes, as well as 30 Gy to the liver. Patients were followed up for time to recurrence and for survival. Fourteen patients were enrolled. One elected not to have radiation after surgery; one died of acute hepatic radiation toxicity after a major deviation from protocol. Of the 12 remaining patients, seven survived longer than 10 years for a survival rate of 58%. Other than the fatal hepatic toxicity, side effects from radiation were moderate and of short duration. One patient failed to complete therapy because of ascites, had two episodes of partial bowel obstruction (successfully treated conservatively), and subsequently survived more than 10 years. Two of three patients with stage C1 tumors, four of eight with C2 tumors, and one with a C3 tumor were long-term survivors. This study demonstrates the feasibility and acceptable toxicity of this adjuvant regimen. The numbers are too limited to evaluate survival, but all seven survivors have lived more than 10 years.