Intraoperative radiotherapy for oncological and function-preserving surgery in patients with advanced lower rectal cancer

Abstract

Pelvic autonomic nerve preservation (PANP) with lateral lymph node dissection (LLND) has been introduced in rectal cancer surgery in Japan; however, its indication has not been standardized yet. Forty-four patients with advanced lower rectal cancer were randomized to either the standard treatment group (control group) or the intraoperative radiotherapy (IORT) group. All patients underwent potentially curative resection of the rectum with total mesorectal excision. The control group underwent bilateral LLND and limited PANP. The IORT group underwent bilateral LLND, complete PANP, and IORT. Patients allocated to the IORT group received IORT to the bilateral preserved pelvic nerve plexuses. Patients' clinicopathologic parameters, postoperative complications, voiding function, and prognosis were compared between the two groups. Among 44 patients enrolled, three patients were excluded from the analysis, resulting in 19 patients in the IORT group and 22 patients in the control group. Patients' demographic and pathological parameters and postoperative complications were well balanced between the two groups. Oncological outcomes including overall and disease-free survival were also similar. Local recurrence was observed in one patient in each group. Among the 34 patients not complicated with intrapelvic abscess, the mean duration of urinary catheter indwelling was 8 days in the IORT group and 13 days in the control group (p = 0.055). In the long term, medication for urination was necessitated in four patients in the control group, whereas in none in the IORT group (p = 0.059). Oncological outcomes in the IORT group are equal to those in the control group, and voiding functions in the IORT group are superior to those in the control group. These results suggest that IORT may be useful to expand the indication of complete PANP with LLND for advanced lower rectal cancer.