Short‐Term Outcomes of Transanal Total Mesorectal Excision for Rectal Cancer: A Multicenter Propensity Score‐Matched Analysis Comparing Patients With and Without Preoperative Neoadjuvant Therapy

Aim To evaluate the association between preoperative neoadjuvant therapy and short‐term outcomes of transanal total mesorectal excision for rectal cancer. Methods We retrospectively analyzed patients who underwent transanal total mesorectal excision at 26 Japanese institutions between 2012 and 2019. Patients who received neoadjuvant therapy were matched 1:1 with patients who did not. Perioperative, postoperative, and pathological outcomes were compared. Results After matching, 294 patients (147 per group) were analyzed. Operative time was longer in the neoadjuvant therapy group than in the non‐neoadjuvant therapy group (median, 510.0 vs. 382.0 min), with an adjusted mean difference of 129.25 min (95% CI, 87.90–170.59; p < 0.001). Clavien–Dindo grade ≥ III complications occurred in 18/147 patients (12.2%) without neoadjuvant therapy and 16/147 (10.9%) with neoadjuvant therapy (adjusted OR, 0.90; 95% CI, 0.44–1.85; p = 0.769). Full‐cohort conventional and Firth logistic analyses and marginal standardization likewise did not identify a statistically significant association. Neoadjuvant therapy remained associated with longer operative time after adjustment for operative procedure, lateral pelvic lymph node dissection, and abdominal approach. Resection‐margin involvement did not differ significantly between groups. Conclusion Neoadjuvant therapy was associated with longer operative time during transanal total mesorectal excision, whereas no statistically significant association with severe postoperative morbidity was detected. Sensitivity analyses likewise did not identify a statistically significant association, supporting the technical feasibility of transanal total mesorectal excision after neoadjuvant therapy in experienced centers.