Prospective Multicenter Comprehensive Survey on Male Sexual Dysfunction following Laparoscopic, Robotic, and Transanal Approaches for Rectal Cancer (the LANDMARC Study)

Objective: To investigate the incidence of male sexual dysfunction (SD) including erectile dysfunction (ErD) and ejaculatory dysfunction (EjD) after minimally invasive rectal cancer surgery. Background: Male SD significantly affects post-rectal cancer surgery quality of life (QOL). Current assessments using the International Index of Erectile Function-5 are unsuitable for patients with reduced postoperative sexual activity, because it assumes sexual intercourse. This study addresses this gap using the Erection Hardness Score (EHS) and custom ejaculatory questionnaires. Methods: This prospective multicenter open-label phase II trial enrolled 399 patients who underwent laparoscopic (Lap), robotic (Ro), or transanal (Ta) rectal cancer surgery. EHS and custom ejaculatory questionnaires assessed ErD, EjD, and potency impairment at 3, 6, and 12 months postoperatively. The rates were assessed in the full analysis set and compared between the Lap and Ro groups after propensity score matching. Results: At 12 months, the overall incidences of ErD and EjD were 34.7% and 29.8%, respectively. The Ro group showed a significantly lower EjD rate (25.0%) than the Lap group (40.9%), with no significant difference in ErD. Potency impairment was lower in the Ro group at 6 months (32.7% vs. 22.3%) and 12 months (29.0% vs. 17.8%) postoperatively. The Ta group showed relatively high ErD and EjD at 3 months, with some recovery at 12 months. Conclusions: Minimally invasive rectal cancer surgery commonly results in ErD, EjD, and potency impairment. Robotic surgery provides lower EjD rates and less potency impairment. Comprehensive sexual function assessments are essential to inform patients and improve QOL outcomes.