Backgrounds: 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. Patients and Methods: Thirty-seven patients with advanced lower rectal cancer were randomized to either the standard treatment group or the intraoperative radiotherapy (IORT) group. All patients underwent potentially curative resection of the rectum with total mesorectal excision. The standard treatment 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 separately. Patients' clinicopathologic parameters, postoperative complications, voiding function, and prognosis were compared between the two groups. Results: Among 37 patients enrolled, 3 patients were excluded from the analysis, resulting in 17 patients in each 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 (6%) in each group. Among the 27 patients not complicated with intrapelvic abscess, the mean duration of urinary catheter indwelling was 8 days in the IORT group, and 15 days in the standard treatment group (p=0.09). In the long-term, medication for urination was necessitated in 4 patients in the standard treatment group, whereas in none in the IORT group (p=0.04). Discussions: Oncological outcomes in the IORT group are equal to those in the standard treatment group, and voiding functions in the IORT group are superior to those in the standard treatment group. These results suggest that IORT may be useful to expand the indication of complete PANP with LLND for advanced lower rectal cancer.
Quality of surgery