Potentially curable rectal cancer is primarily treated with surgical resection. Adjuvant or neoadjuvant radiotherapy is often utilized for patients deemed to be at unacceptable risk for local recurrence. The purpose of this article is to review the pertinent literature and elucidate the role of radiotherapy in patients with an intermediate risk of local recurrence. The addition of chemoradiotherapy is recommended in the majority of patients with transmural or node positive rectal cancer. However, some patients with favorable characteristics may have only a small incremental benefit from the addition of radiotherapy. The decision to treat or not to treat should take into consideration the patient and physician tolerance of risk of recurrence and risk of treatment related toxicity. The primary factors identified for determining low risk patients are circumferential radial margin (CRM), location within the rectum, and nodal status. Patients at lowest risk have widely negative CRM (>2mm), proximal lesions (>10cm from the anal verge), and no nodal disease. Patients with all three low risk factors have an absolute reduction in local recurrence that is <5% and may be eligible to forego radiotherapy. Additional factors identified which may impact local recurrence risk are elevated serum CEA level, lymphovascular space invasion, pathologic grade, and extramural space invasion.
Keywords: Scombined modality therapy; adjuvant therapy; neoadjuvant chemoradiation; radiation therapy; rectal cancer.