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/m) 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/m vs < 30 kg/m) 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.