Contraception, Hormones, and Cancer: Exploring the Link Between Birth Control and Cancer Risk

Breast and ovarian cancers remain major health concerns worldwide. Contraceptive methods, particularly hormonal agents, have been implicated in affecting cancer risk, yet their associations remain debated. This study investigated the relationship between commonly used hormonal and non-hormonal contraceptive methods and the risk of breast and ovarian cancer. Clinical data were obtained from the All of Us Research Program. Female participants were stratified into exposure groups based on contraceptive method, including oral contraceptives (OC, hormonal), intrauterine devices (IUDs, hormonal), tubal ligation (TL, non-hormonal), and non-invasive (NI, non-hormonal) methods. Cancer diagnoses occurring at least six months after contraceptive initiation were included. The final analytic cohort comprised 888 cases, of which 811 reported OC use, 67 IUD use, 20 TL use, and 12 NI use. In total, 763 cases of breast cancer and 127 cases of ovarian cancer were identified. Associations were quantified using a Jaccard similarity matrix, which revealed that oral contraceptives demonstrated the strongest overlap with cancer incidence ( J = 0.945), particularly breast cancer ( J = 0.812), while showing a weaker association with ovarian cancer ( J = 0.147). In contrast, IUDs, TL, and NI methods displayed minimal similarity with cancer outcomes ( J ≤ 0.075). These findings suggest that oral contraceptives are most strongly associated with breast cancer risk, whereas non-hormonal methods, including TL and NI, showed no clear associations with cancer outcomes.