Anti-Obesity Medications and the Risk of Obesity-Related Cancers in Older Women: A Propensity Score Matching Analysis of 2007–2015 SEER-Medicare Data

Background/Objectives: The increasing prevalence of obesity has led to a growing interest in anti-obesity medications (AOMs). While these medications have shown promise in aiding weight loss, their potential impact on reducing obesity-related cancers (ORCs) incidence remains poorly understood, particularly among women over 65 years of age. This study examined the association between the use of AOMs and the risk of ORCs in this population. Methods: A retrospective cohort study was conducted using 2007–2015 SEER-Medicare data, including 10,830 women aged ≥65 years in a 1:2 propensity-score matching design. The primary exposure was AOM use, with additional analyses focused specifically on phentermine and liraglutide exposure. Conditional multivariable Cox proportional hazards models were conducted. Results: We found an inverse association between the use of AOMs and the risk of ORCs (aHR: 0.78; 95% CI: 0.73–0.84; p < 0.001). Similar findings were observed in cancer-specific sites analysis, advanced-stage ORCs (aHR: 0.76; 95% CI: 0.65–0.89; p < 0.001), breast (aHR: 0.84; 95% CI: 0.77–0.91; p < 0.001), colorectal (aHR: 0.82; 95% CI: 0.71–0.96; p = 0.010), and advanced-stage colorectal cancers (aHR: 0.71; 95% CI: 0.54–0.91; p < 0.001). In secondary analyses, phentermine was inversely associated with the risk of ORCs, breast, and endometrial cancers, but no associations with liraglutide were observed. Conclusions: The use of AOMs, including phentermine, was inversely associated with ORCs and some cancer-specific sites in a cohort of older women. Further prospective studies are warranted to validate these findings among women of different age groups and to identify the underlying biological mechanisms.