Risk Factors for Conversion to an Open Surgery during Laparoscopic Surgery for Patients with Colon Cancer with Body Mass Index 25 kg/m2

Objectives: The purpose of this study was to identify factors associated with conversion to an open procedure during laparoscopic colectomy in patients with body mass index (BMI) 25 kg/m2. The effects of conversion on long-term outcomes were evaluated. Methods: In a multicenter cohort study conducted under the auspices of the Japan Society of Laparoscopic Colorectal Surgery, clinicopathological data were examined for 887 patients with BMI 25 kg/m2 who underwent laparoscopic surgery for colon cancer. Risk factors for conversion to an open procedure were estimated using a logistic model after parameter selection using a least absolute shrinkage and selection operator (lasso) model. Long-term outcomes were compared after inverse probability weighting (IPW) estimation. Results: Among the 887 patients who underwent laparoscopic colectomy, 31 patients (3.5%) required conversion to an open procedure. In multivariate analysis, preoperative BMI 27.5 kg/m2, comorbidity-hypertension, blood loss, and simultaneous resection of adjacent organs were independent factors for conversion. After IPW estimation, there were no significant differences in recurrence-free, cancer-specific and overall survival between the conversion (+) and (-) groups. Conclusions: In obese patients with the factors identified in this study, surgeons should consider the possibility of conversion to open surgery. Long-term outcomes in patients with BMI 25 kg/m2 did not differ between patients who underwent conversion and those who did not. Therefore, conversion to an open procedure was not detrimental in Japanese patients with BMI 25 kg/m2.