Obesity Selectively Increases Intraoperative Risk in Left-Sided Colon Cancer Surgery: A Retrospective Cohort Study.

Background: Obesity is traditionally viewed as a risk factor for adverse surgical outcomes. This study evaluated whether obesity (BMI ≥ 30 kg/m²) independently affected intraoperative and postoperative outcomes following colon cancer resection, and whether these effects varied by anatomical site.

Methods: A retrospective cohort study was conducted of consecutive patients who underwent colon cancer resection at a single institution from 2015 to 2022. Patients were stratified by BMI (≥ 30 kg/m² vs < 30 kg/m²) and further grouped by urgency (elective or emergency) and anatomical subsite (right- vs left-sided). Primary outcomes were intraoperative complications, severe postoperative morbidity (Clavien-Dindo ≥ III), conversion to open surgery, ICU admission, and 30-day mortality. Multivariate logistic regression was used to adjust for confounders.

Results: Among the 737 patients, 33.5% were obese (BMI ≥ 30). Obese patients were younger and had higher rates of hypertension (55% vs 46%, p = 0.01), diabetes (25% vs 16%, p < 0.01), and respiratory disease (22% vs 11%, p < 0.01). In the overall cohort, obesity was not associated with increased rates of intraoperative complications, severe postoperative complications, conversion to open surgery, or 30-day mortality. In elective resections, obesity was independently associated with increased likelihood of ICU admission (aOR 1.82, 95% CI 1.08-3.09; p = 0.02), while in emergent resections obesity was independently associated with higher intra-operative complications (aOR 2.18, 95% CI 1.19-3.97; p = 0.01). Stratified analysis by resection site revealed that obesity was an independent risk factor associated with intraoperative complications (aOR 1.89, 95% CI 1.03-3.47; p = 0.04) and ICU admission (aOR 3.17, 95% CI 1.61-6.23; p < 0.01) following left-sided colectomy, but not right-sided surgery.

Conclusions: Obesity was not associated with adverse outcomes following colon cancer surgery overall. However, when stratified by anatomical subsite, obesity was independently associated with increased perioperative risk in left-sided resections. These findings support a more nuanced approach to operative planning and perioperative risk stratification.