Effects of postoperative adjuvant radiotherapy on recurrence and survival in stage III rectal cancer.

BACKGROUND: The aim of this study is to evaluate whether the addition of radiotherapy to chemotherapy would enhance the benefits obtained with chemotherapy alone, in stage III rectal cancer in the era of preoperative chemoradiotherapy and total mesorectal excision (TME).
METHODS: From January 1999 to January 2008, 300 stage III rectal cancer patients who underwent TME were prospectively identified; a total of 46 patients who received preoperative chemoradiotherapy or did not receive adjuvant therapy were excluded. Patients who received postoperative chemotherapy alone (n=190) and those who received postoperative chemoradiotherapy (n=64) were compared.
RESULTS: The median follow-up period was 52 (range, 4-129) months. Patients receiving radiotherapy were younger and had a higher percentage of advanced pT category or perineural invasion than patients who did not. The estimated 5-year local recurrence-free survival rate was radiotherapy 92% with radiotherapy and 86% without. The disease-free survival rate was 55% with radiotherapy compared to 57% without and the overall survival rates were similar (63% vs. 68%, all P>0.05). In patients with a positive circumferential resection margin or insufficient distal resection margin, the local recurrence-free, disease-free, and overall survival rates were unaffected by radiotherapy.
CONCLUSIONS: The addition of postoperative radiotherapy to chemotherapy did not reduce the recurrence or mortality in node-positive rectal cancer when compared with chemotherapy alone. Moreover, this approach may not compensate for a positive circumferential resection margin or insufficient distal resection margin following rectal cancer surgery.