BMI and Initiation of Cancer Screening: A Closer Look at Differences by Race, Ethnicity, and Sex in a Multicenter Population

Introduction: Obesity is associated with a risk for several screen-detectable cancers, yet cancer screening rates are lower among adults with obesity. It is unclear whether associations between BMI and screening initiation differ by race, ethnicity, or sex. Methods: A retrospective cohort study was conducted among adults initiating cervical, colorectal, or lung cancer screening using electronic health record data from 10 U.S. health systems (2010–2020 for the cervical/colorectal cohorts; 2014–2021 for lung). Associations between screening initiation (within 15 months of becoming age eligible) and BMI categories were analyzed using separate logistic regression models. Effect modification by race/ethnicity and sex was assessed. Data were analyzed from 2023 to 2025. Results: Among 23,849 adults eligible for cervical cancer screening, patients with overweight (BMI of 25 to <30 kg/m2), Class 1 obesity (BMI of 30 to <35 kg/m2), Class 2 obesity (BMI of 35 to <40 kg/m2), and Class 3 obesity (BMI of ≥40 kg/m2) had lower odds of screening initiation than adults with a healthy weight (BMI of 18.5 to <25 kg/m2). Similarly, among 561,132 adults eligible for colorectal cancer screening, overweight and Classes 1–3 obesity were associated with lower odds of screening. Race and ethnicity moderated the associations between BMI and cervical (p=0.0013) and colorectal (p<0.0001) screening, and sex moderated the associations between BMI and colorectal screening (p<0.0001). Stratified analysis was not conducted for the lung cohort (49,199) owing to a smaller sample size. Conclusions: Adults with obesity have lower odds of timely screening initiation. Given the increased risk of cancers in adults with obesity, effective interventions to target suboptimal cancer screening are critically important.