Muna Al-Khaifi, Lead of Breast Cancer Survivorship Program and GP oncologist, Skin Cancer Clinic at Sunnybrook, shared a post on LinkedIn about a paper by Hadizadeh F. et al. published in the Journal of Clinical Oncology:
“Evidence in Perspective: Hormonal Contraception and Breast Cancer Risk
A large JAMA Oncology (2025) cohort study of ~2 million women (ages 15–49) found that current hormonal contraceptive users had a 25% higher relative risk of breast cancer (HR 1.24; 95% CI 1.20–1.28) compared with non-users.
After a median follow-up of 8 years, 9,249 cases were identified.
By formulation, risk was 18% higher with combined estrogen–progestin (HR 1.12) and 22% higher with progestin-only (HR 1.21).
Importantly, the study showed that breast cancer risk varies by progestin content, providing evidence to support more informed and individualized contraceptive counselling.
Absolute Risk in Perspective:
Although relative risk increased modestly, the absolute excess risk was very low — about +4 additional cases per 100,000 women per year.
• Ages 15–35: ≈ +2 cases / 100,000 per year
• Ages 36–49: ≈ +8 cases / 100,000 per year
The risk declined after discontinuation, returning to baseline within a few years.
Clinical Implications:
• The risk increase is very small, transient, and age-dependent.
• Variability by progestin type highlights the importance of personalized prescribing.
• Emphasizing absolute vs. relative risk helps contextualize the findings for patients.
• Risk normalization after discontinuation supports the long-term safety of hormonal contraception.
• Hormonal contraception remains a safe, effective, and empowering choice when guided by balanced, evidence-based counselling.”
Title: Hormonal Contraceptive Formulations and Breast Cancer Risk in Adolescents and Premenopausal Women
Authors: Fatemeh Hadizadeh, Ardita Koteci, Torgny Karlsson, Weronica E. Ek, Asa Johansson.
You can read the full article in JAMA Oncology.
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