Background: The optimal RT fractionation and the timing of surgery in resectable locally advanced rectal carcinoma is still debatable. Postponing the time of surgery after SCRT seems to be more beneficial in inducing down-staging, and reducing postoperative morbidity than SCRT with immediate surgery. IMRT is used successfully in many cancers helping to achieve better conformality.

Objectives: The study aimed to evaluate the efficacy and tolerability of preoperative short-course IMRT with delayed surgery in patients with resectable locally advanced rectal carcinoma.

Patients and methods: Patients with resectable locally advanced rectal carcinoma were treated with preoperative short-course IMRT (25 Gy over 5 fractions) followed by surgery after 4-8 weeks.

Results: 37 patients were included, down-staging was observed in 54.1% of them; patients with cN2 disease, radiological EMVI, and radiologically involved mesorectal facia (MRF) tend to have a statistically significant less down-staging. severe early and late toxicity was reported in 5.4% and 8.1% of the patients respectively, and 37 % had postoperative complications. 33 patients (94.6%) had curative surgery, 9% had pCR, and sphincter sparing was achieved in 28% of patients with low rectal tumors. Cumulative 2 years DFS and OS were 71 % and 80 % respectively.

Conclusion: SCRT with delayed surgery is a valid convenient, safe, and economically beneficial option in the treatment of locally advanced resectable rectal carcinoma, utilization of IMRT can help in reducing the dose to organs at risk. Further studies with a larger number of patients are mandatory to identify the most suitable patients for this approach.