Role of external irradiation in high-risk resected colon cancer

BACKGROUND / AIM: The best therapeutic modality for colon cancer "one of the most common malignancies of human being" is surgical resection of primary tumor. Adjuvant chemotherapy can help surgery to have a higher control and survival rate in high-risk resected patients, but the role of radiation therapy is the place of debate. This study was carried out to evaluate the possible role of adjuvant radiotherapy in such cases.
MATERIALS AND METHODS: This retrospective trial evaluated 65 eligible patients with surgically resected high-risk colon carcinoma (serosal and/or lymph node involvement), from May 1986 to February 2000. The patients were categorized into two groups. The first group was treated with chemotherapy alone and the other with chemo-radiotherapy. Chemotherapy included 5.FU 500 mg/m²/5days for 6-8 courses and radiotherapy consisted 45-55 Gy with 1.5-2 Gy/fraction. Minimum follow-up was 36 months.
RESULTS: Mean event-free survival was 140 and 101 months in chemotherapy and combined-therapy groups, respectively (P = 0.099). Local recurrence rate was detected as 9.7% in the chemotherapy arm and 23.5% in the combined-therapy arm (P > 0.1). Treatment-related morbidity and mortality has been significantly higher in the radiation arm (P < 0.001) .
CONCLUSION: Postoperative external radiation as adjuvant treatment does not improve local control of the patients with colon carcinoma.

Keywords
Colon cancer, Radiation therapy, Surgical resection, Chemotherapy, Adjuvant treatment