Prospective single-arm study of intraoperative radiotherapy for locally advanced or recurrent rectal cancer

This study aims to evaluate the feasibility and outcomes of intraoperative radiotherapy (IORT) using high-dose-rate (HDR) brachytherapy for locally advanced or recurrent rectal cancers. Despite preoperative chemoradiation, patients with locally advanced or recurrent rectal cancers undergoing surgery remain at high risk of local recurrence. Intensification of radiation with IORT may improve local control.

This is a prospective non-randomised study. Eligible patients were those with T4 rectal cancer or pelvic recurrence, deemed suitable for radical surgery but at high risk of positive resection margins, without evidence of metastasis. Chemoradiation was followed by radical surgery. Ten gray (Gy) was delivered to tumour bed via an IORT applicator at time of surgery.

There were 15% primary and 85% recurrent cancers. The 71% received preoperative chemoradiation. R0, R1 and R2 resections were 70%, 22% and 7%, respectively. IORT was successfully delivered in 27 of 30 registered patients (90% (95% confidence interval (CI) = 73-98) ) at a median reported time of 12 weeks (interquartile range (IQR) = 10-16) after chemoradiation. Mean IORT procedure and delivery times were 63 minutes (range 22-105 minutes). Ten patients (37% (95% CI = 19-58) ) experienced grade 3 or 4 toxicities (three wound, four abscesses, three soft tissue, three bowel obstructions, three ureteric obstructions and two sensory neuropathies). Local recurrence-free, failure-free and overall survival rates at 2.5 years were 68% (95% CI = 52-89), 37% (95% CI = 23-61) and 82% (95% CI = 68-98), respectively.

The addition of IORT to radical surgery for T4 or recurrent rectal cancer is feasible. It can be delivered safely with low morbidity and good tumour outcomes.