Five-year oncological outcomes after selective neoadjuvant radiotherapy for resectable rectal cancer

Introduction: There is considerable variation in selection of patients for and type of neoadjuvant radiotherapy administered in the treatment of resectable rectal cancer. The aim of this study was to report outcomes for patients with resected rectal cancer from a unit with step-wise selection for surgery alone, short course radiotherapy (SCRT) or downstaging long course chemoradiotherapy (LCCRT).

Material and methods: Cohort analysis of patients with rectal adenocarcinoma resected with curative intent between 2008 and 2012 at a specialist regional colorectal surgery center. The primary endpoints were local recurrence, metastatic recurrence, disease-free survival and overall survival. Exploratory uni- and multi-variable regression analyses were performed to identify predictive factors.

Results: About 240 patients were treated by surgery alone, 90 patients received SCRT and 91 patients received LCCRT. Five-year local recurrence was 10.8% in the surgery alone group, 3.3% with SCRT and 18.7% with LCCRT. Metachronous distant metastasis was highest in the SCRT group (13.8% surgery alone, 25.6% SCRT, 15.4% LCCRT). Uni- and multi-variable regression analysis found that local and distant recurrence was attributable predominantly to adverse tumor biology.

Conclusions: Patients selected for SCRT had a lower rate of local recurrence than patients selected for surgery alone, but were more likely to develop distant metastasis. There was no difference in overall survival. With low local recurrence rates, distant metastasis is the predominant risk for patients with resectable rectal cancer.