The role of intraoperative radiotherapy in advanced rectal cancer: a meta-analysis

Patients with locally advanced and locally recurrent rectal cancer (LARC/LRRC) experience higher rates of local recurrence (LR) and poorer overall survival than patients with primary rectal cancer restricted to the mesorectum despite improved neoadjuvant treatment regimens and radical surgical procedures. Intraoperative radiotherapy (IORT) has been suggested as an adjunctive tool in the surgical management of these challenging cases. However, clear evidence regarding the oncological benefit of IORT is sparse. The aim of this review was to update this evidence in the era of standardized neoadjuvant radiotherapy administration.

A systematic review of patients who received IORT as part of multimodal treatment for advanced rectal cancer from 2000 to 2020 and an analysis of IORT and surgery/external beam radiotherapy (EBRT) groups was performed. The primary endpoint was the rate of LR between the two groups.

Seven papers met the predefined criteria. LR was reduced by the addition of IORT when compared with the surgery/EBRT alone group (14.7% vs. 21.4%; OR 0.55, 95% CI 0.27-1.14; p = 0.11). There was no increase in reported genitourinary morbidity, wound issues, pelvic collections or anastomotic leak in those patients who received IORT. Notably, there was no survival difference between the two groups.

The addition of IORT to current treatment strategies in the management of patients with LARC/LRRC is associated with a lower rate of locoregional recurrence without increased morbidity. However, this marks a highly selective group of patients, with heterogeneity regarding indications, prior neoadjuvant treatments and/or IORT dosing.