Objectives: The role of chemoradiotherapy in patients with pT3N0M0 rectal cancer is controversial. Intraoperative radiotherapy (IORT) has the ability to deliver a high, single-fraction radiation dose to tumor bed with minimal exposure of surrounding tissues. On the basis of the literature, the local failure pattern occurs mostly in the presacral-perineal space rather than the regional lymph node after adjuvant chemoradiation for T3N0 rectal adenocarcinoma. Our aim was to evaluate the efficacy of IORT followed by adjuvant chemotherapy in the treatment of pT3N0M0 rectal adenocarcinoma.
Materials and Methods: A total of 91 consecutive patients with newly diagnosed pT3N0M0 well-differentiated and moderately differentiated rectal adenocarcinoma were enrolled: 46 patients received adjuvant concurrent chemoradiotherapy (external beam radiotherapy [EBRT group]) and 45 patients received IORT (dose range, 15 to 25 Gy), followed by identical systemic chemotherapy (IORT group).
Results: The 5-year locoregional control rate, overall survival, and disease-free survival were 86%, 86%%, and 73% in the EBRT group versus 84%, 84%, and 71% in the IORT group, respectively (P>0.05). Compared with the EBRT group, the incidence of acute grade 3 toxicity was significantly lower in the IORT group than in the EBRT group (P<0.05). There were no severe late complications observed in the IORT group.
Conclusions: IORT followed by adjuvant chemotherapy for pT3N0M0 rectal adenocarcinoma provided a similar outcome in terms of local control, overall survival, and disease-free survival, as compared with concurrent chemoradiotherapy after surgery. However, no significant acute or late complications were observed in patients treated with IORT. Further investigation, preferably in a prospective manner, is warranted to confirm the efficacy of IORT in the treatment of nonmetastatic T3 rectal cancer.