A recent cohort study of more than 2 million adolescent girls and women has provided the most comprehensive evaluation to date of hormonal contraceptive use and breast cancer risk. The study followed 2,095,130 participants for a total of 21,020,846 person-years, during which 16,385 breast cancer cases were reported.
Key Findings
Ever use of any hormonal contraceptive was associated with an increased risk of breast cancer (HR 1.24; 95% CI, 1.20–1.28), corresponding to 1 additional case per 7,752 users (95% CI, 5,350–14,070). Both combined oral contraceptives (HR 1.12; 95% CI, 1.07–1.17) and progestin-only formulations (HR 1.21; 95% CI, 1.17–1.25) were linked to elevated risk.
Specific formulations showed varying levels of association:
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Oral desogestrel-only: HR 1.18 (95% CI, 1.13–1.23)
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Oral desogestrel-combined: HR 1.19 (95% CI, 1.08–1.31)
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Etonogestrel implants (active metabolite of desogestrel): HR 1.22 (95% CI, 1.11–1.35)
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Levonorgestrel-containing combined pills: HR 1.09 (95% CI, 1.03–1.15)
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Levonorgestrel 52 mg intrauterine system: HR 1.13 (95% CI, 1.09–1.18)
No statistically significant increased risk was observed for medroxyprogesterone acetate injections, etonogestrel vaginal rings, or combined oral drospirenone, despite high usage numbers.
“This cohort study, to our knowledge, is the largest and most comprehensive study to date with extended follow-up and broad coverage of various progestin types,: noted the authors. “Findings of this cohort study highlight that breast cancer risk varies substantially by progestin content in hormonal contraceptives, providing valuable insights to support more informed contraceptive prescription”.
Clinical Implications
These findings provide important context for clinicians and patients when discussing contraceptive options. While the absolute increase in risk is small, understanding the relative differences between contraceptive types may help in individualised decision-making. The study underscores the need for ongoing research to clarify the risk profiles of newer hormonal formulations and long-term outcomes.
Paper: Hadizadeh, F., et al. Hormonal Contraceptive Formulations and Breast Cancer Risk in Adolescents and Premenopausal Women. JAMA Oncology. Published online October 30, 2025. Access online here.