Robotic-assisted resection for beyond TME rectal cancer: a novel classification and analysis from a specialized center.

Locally advanced rectal cancer often requires an extended resection beyond the total mesorectal excision plane (bTME) to obtain clear resection margins. We classified three types of bTME rectal cancer following local disease diffusion: radial (adjacent pelvic organs), lateral (pelvic lateral lymph nodes) and longitudinal (below 3.5 cm from the anal verge, submitted to intersphincteric resection). The primary aim of this study was to evaluate the application of robotic surgery to the three types of bTME regarding the short and long-term oncological outcomes. Secondary aim was to identify survival prognostic factors for bTME rectal cancers. A total of 137 patients who underwent robotic-assisted bTME procedures between 2008 and 2018 were extracted from a prospectively collected database. Patient-related, operative and pathological factors were assessed. Morbidity was moderately high with 66% of patients reporting postoperative complications. Median follow up was 47 months (IQR, 31.5-66.5). Local recurrence rate was 15.3% with a statistical difference between the three types of bTME (p = 0.041). Disease progression/distant metastasis rate was 33.6%. Overall survival was significantly different (p = 0.023) with 1- and 3-years rates of: 77.8% and 55.0% (radial; n = 19); 96.6% and 84.8% (lateral; n = 30); 97.7% and 86.9% (longitudinal; n = 88). No statistical difference was observed for disease-free survival (p = 0.897). Local recurrence-free survival was significantly different between the groups (p = 0.031). Multivariate analysis showed that (y)pT (p = 0.028; HR (95% CI) 5.133 (1.192-22.097)), (y)pN (p = 0.014; HR (95% CI) 2.835 (1.240-6.482)) and type of bTME were associated to OS whilst (y)pT (p = 0.072) and type of bTME were not associated to LRFS.