MRI pelvimetry-based evaluation of surgical difficulty in laparoscopic total mesorectal excision after neoadjuvant chemoradiation for male rectal cancer

PURPOSE: Laparoscopic total mesorectal excision (LaTME) is technically demanding in rectal cancer after neoadjuvant chemoradiotherapy (NCRT). This study aimed to predict the surgical difficulty of LaTME after NCRT based on pelvimetric parameters. METHODS: This study enrolled 147 patients who underwent LaTME after NCRT. The surgical difficulty was graded as high or low according to the operative time, estimated blood loss, conversion to open surgery, postoperative hospital stay, and postoperative complications. Pelvimetry parameters were collected based on preoperative MRI. A logistic regression analysis was performed to identify predictors of high surgical difficulty, and a nomogram was developed. RESULTS: Totally, 18 (12.2%) patients were graded as high surgical difficulty. High surgical difficulty was correlated with a shorter interspinous distance (P = 0.014), a small angle α and γ (P = 0.008, P = 0.008, respectively), and a larger mesorectal area and mesorectal fat area (P = 0.041, P = 0.046, respectively). Tumor distance from the anal verge (OR = 0.619, P = 0.024), tumor diameter (OR = 3.747, P = 0.004), interspinous distance (OR = 0.127, P = 0.007), and angle α (OR = 0.821, P = 0.039) were independent predictors of high surgical difficulty. A predictive nomogram was developed with a C-index of 0.867. CONCLUSION: A shorter tumor distance from the anal verge, larger tumor diameter, shorter interspinous distance, and smaller angle α could help to predict high surgical difficulty of LaTME in male LARC patients after NCRT. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00595-020-02211-3.