Background: CRC sidedness has recently been recognized as a significant prognostic factor for survival; left-sided colorectal cancer (LCRC) is associated with superior outcomes as compared to right-sided colon cancer (rCC). Although obesity has long been recognized as a risk factor for CRC, the influence of obesity on CRC sidedness remains to be elucidated. To evaluate the effect of obesity on CRC sidedness and determine how race, age, and sex affect mortality among individuals with obesity and CRC. Methods: A survey-weighted analysis was conducted using data obtained from the National Inpatient Sample (NIS) between 2016 and 2019. Results: Of the 24,549 patient discharges included in the cohort with a diagnosis of CRC and a reported body mass index (BMI), 52.6% were LCRC and 47.5% were rCC. The race distribution was 67.7% White, 17.6% Black, 10.0% Hispanic, and 4.8% Other (American Indian, Asian, Pacific Islander, or Alaskan Native). Overweight and obese individuals were more likely to have rCC as compared to normal weight patient discharges [adjusted OR (aOR) = 1.28; 95% CI:1.17 – 1.39 and aOR = 1.45; 95% CI:1.37 –1.54, respectively). In addition, among the obese population, Blacks were more likely to have rCC as compared to Whites (aOR = 1.23; 95% CI: 1.09 – 1.38). Normal weight, overweight, and obese individuals in the “Other” race category had increased odds of death as compared to all other races (aOR=1.18; 95% CI:1.13-1.22; aOR=1.09 95% CI: 0.99-1.19; and aOR=1.19; 95% CI: 1.13-1.25, respectively). Overweight and obese patient discharges over the age of 65 years were more likely than their younger counterparts to present with rCC. As compared to males, females had a higher likelihood of presenting with rCC irrespective of weight, but lower mortality across all weight categories (Table). Conclusions: Obesity is associated with an increased risk of rCC. Racial disparities in CC sidedness and outcomes are particularly pronounced among the overweight and obese population. Investigation into causes of these disparities may help improve outcomes among all individuals with CRC.

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