Analysis of conversion factors in robotic-assisted rectal cancer surgery

Robotic surgical management of rectal cancer has a series of advantages which might facilitate the surgical approach to the pelvic cavity and reduce conversion rates. The aim of the present study is to identify independent factors for conversion during robotic rectal cancer surgery.

A total of 67 patients underwent preoperative CT scan in order to obtain a three-dimensional image of the pelvis, the tumour and prostate. We measured maximum and minimum ilio-iliac, sacral promontory-pubis, coccyx-pubis diameters and maximum lateral axis. Further variables under consideration were age, BMI and use of neoadjuvant therapy. We recorded short-term follow-up outcomes of the resected tumour.

The present study included 67 patients (39 males) with an average age of 65.11 ± 10.30 years and a BMI of 27.70 ± 3.97 kg/m(2). Operative procedures included nine abdominoperineal resections and 58 low anterior resections. There were 15 (22.38 %) conversions. Mean operating time was 192.2 ± 42.73 min. Minimum ilio-iliac, maximum ilio-iliac, promontory-pubic and coccyx-pubis diameter as well as maximum lateral axis were 100.38 ± 7.65, 107.10 ± 10.01, 109.97 ± 9.20, 105.61 ± 9.27 and 129.01 ± 9.94 mm, respectively. Mean tumour volume was 37.06 ± 44.08 cc; mean prostate volume was 42.07 ± 17.49 cc. The univariate analysis of the variables showed a correlation between conversion and BMI and minimum ilio-iliac and coccyx-pubis diameters (p = 0.004, 0.047, 0.046). In the multivariate analysis, the only independent predictive factor for conversion was the BMI (p = 0.004).No correlation was found between conversion and sex, age, tumour volume or the rest of pelvic diameters.

BMI is an independent factor for conversion in robotic-assisted rectal cancer surgery.