Role of Adjuvant Radiotherapy in Locally Advanced Colonic Carcinoma in the Modern Chemotherapy Era

Background. The role of adjuvant radiation therapy (RT) in the treatment of resected, locally advanced colon cancer is unclear. One randomized controlled trial (Intergroup-0130) addressed this question but failed to meet its accrual goals. Since this trial, few attempts have been made to reassess the role of RT in this clinical setting. Methods. Sixty-two patients with non-metastatic, American Joint Committee on Cancer 7th edition stage T4 colonic adenocarcinoma were treated at our institution between 2000 and 2013. All underwent curative-intent surgery. Sixteen patients underwent resection only, 33 patients received adjuvant chemotherapy (ChT), and 13 patients received adjuvant chemoradiation therapy (CRT). Results. Patients receiving adjuvant CRT were more likely to have T4b (vs. T4a) disease and were more likely to undergo R1 or R2 resection compared with those receiving adjuvant ChT alone. Despite this, multivariate analysis demonstrated that treatment with adjuvant CRT (vs. adjuvant ChT) enhanced locoregional control and disease-free survival (hazard ratio 0.044 and 0.145, respectively; p < 0.05). Conclusions. Adjuvant RT for T4 colon cancers may be appropriate in select patients, specifically those with T4b lesions and/or residual disease following resection.