Abstract B098: Adiposity measures and obesity-related cancer: A report from the Oklahoma Strong Heart Study and Strong Heart Family Study
Authors: Janitz Amanda E. , Reese Jessica A. , Leidner Jean A. , Campbell Janis E. , Fretts Amanda M. , Rhoades Dorothy A. 
Published: December 2023

Abstract
Background: Obesity, defined as a body mass index (BMI) ≥30 kg/m2, disproportionately affects American Indian (AI) people and is increasingly implicated in the incidence of certain cancers. Indeed, while obesity-related cancers account for 43% of incident cancers among all Americans, they account for 51% of incident cancers among AI people. Emerging evidence indicates that body fat distribution (e.g., central vs. peripheral) is associated with cancer independent of BMI. AI adults have a higher prevalence of central adiposity than other populations, yet prospective measures of adiposity associated with increased risk of obesity-related cancer over time in AI people remain limited. Methods: We partnered with the Strong Heart Study/Strong Heart Family Study (SHS/SHFS) and the Oklahoma Central Cancer Registry to link study cohort records with cancer surveillance records from 1997-2019 to systematically classify cancer incidence among cohort participants. We evaluated baseline measures of adiposity, including waist circumference (females cutpoint at 88 cm, males cutpoint at 102 cm) waist-to-hip ratio (females cutpoint at 0.85, males cutpoint at 0.90), and percent body fat (females cutpoint at 35%, males cutpoint at 25%), by the presence of incident obesity-related cancer. We classified survival time as time from the baseline exam date to cancer diagnosis, death, or the end of the study period, whichever occurred first. Participants without a cancer event were censored. To compare survival time by each adiposity measure, we used the log-rank test and generated Kaplan-Meier curves. Results: We identified 140 participants with an obesity-related cancer that linked with a cancer registry record (n=1956 without cancer). The average age at the baseline SHS/SHFS exam was 54 years for those with cancer and 48 years for those without cancer. The average age at cancer diagnosis was 69 years. The most common forms of obesity-related cancer were colorectal (n=40, 29%) and post-menopausal female breast cancer (n=35, 25%). We observed a higher incidence of obesity-related cancer among those with high waist circumference (7.8% v. 4.3%), high waist-to-hip ratio (7.5% vs. 4.2%), and high percent body fat (7.4% v. 4.6%) compared with lower levels of these adiposity measures. We observed differences in time to cancer by waist circumference (p=0.004), waist-to-hip ratio (p=0.03), and percent body fat (p=0.03). Discussion: We observed significant differences in time to cancer diagnosis by multiple adiposity measures within the SHS/SHFS in Oklahoma. As a next step, we plan to link with the other SHS/SHFS sites in the Dakotas and Arizona. This study will provide a solid foundation upon which to base interventions to ameliorate risk factors for obesity-related factors in this underserved population.
Citation Format: Amanda E. Janitz, Jessica A. Reese, Jean A. Leidner, Janis E. Campbell, Amanda M. Fretts, Dorothy A. Rhoades. Adiposity measures and obesity-related cancer: A report from the Oklahoma Strong Heart Study and Strong Heart Family Study [abstract]. In: Proceedings of the 16th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2023 Sep 29-Oct 2;Orlando, FL. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2023;32(12 Suppl):Abstract nr B098.