Sarah George - Department of Reproductive Health
Currently, contraceptive use has been linked to increasing breast cancer risks, leading researchers to aim their investigative efforts towards this correlation (or lack thereof). A comparative meta-analysis using a UK patient database (Clinical Practice Research Data or CPRD) had a case-control study of around 10,000 women aged less than 50 years who were diagnosed with breast cancer between 1996 and 2017. The researchers were aiming to identify the breast cancer risk associated with progesterone-only and combined contraceptives.
In their results, over 44% of women with breast cancer had a hormonal contraceptive prescription for about 3 years before their breast cancer diagnosis. Surprisingly, around 50% of the prescriptions were progesterone-only contraceptives. The meta-analysis also found a significant relative risk for current use or past use of progesterone-only contraceptives with breast cancer. This risk was assessed irrespective of whether the preparation last used was oral progesterone, injected progesterone, progesterone implant, or a progesterone intrauterine device.
Overall, this study found a relative 20 to 30% increase in breast cancer risk associated with combined oral and progesterone-only contraceptives. Given the severity of this cancer diagnosis and the increase in risk with these prescriptions, future research must be geared towards identifying the exact mechanism of this associated risk of cancer. As women are increasingly using contraceptives for family planning and endocrine concerns, women’s health is at risk with these prescriptions. Though physicians may prescribe contraceptives, the supposed health benefits may be underscored if there is also a risk for cancer.
References:
Fitzpatrick D, Pirie K, Reeves G, Green J, Beral V (2023) Combined and progestagen-only hormonal contraceptives and breast cancer risk: A UK nested case–control study and meta-analysis. PLOS Medicine 20(3): e1004188. https://doi.org/10.1371/journal.pmed.1004188
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