NAIROBI, Kenya – An international study has found that hormonal contraceptives may slightly increase the risk of breast cancer, adding new evidence to ongoing debates over the safety of widely used birth control methods.
The study, published in JAMA Oncology, tracked over 2 million women aged 13 to 49 for more than 21 million person-years, revealing that women who used hormonal contraceptives—particularly those containing higher levels of progestin—had a higher incidence of breast cancer compared to non-users.
Researchers estimated that hormonal contraceptive users face about a 12% higher risk when using combined estrogen-progestin pills and up to 21% higher risk for some progestin-only pills such as desogestrel.
Although the individual risk remains low, the findings are considered significant at the population level, given that millions of women worldwide rely on these medications.
The increase translates to around 13 additional breast cancer cases per 100,000 women each year among users.
“The risk is small for any one woman, but because hormonal contraceptives are so widely used, even modest increases have major public health implications,” researchers noted.
Widespread use in Kenya
In Kenya, hormonal contraceptives are the most common form of family planning, used by about 57% of married women as of 2022.
By 2024, an estimated 6.43 million Kenyan women were using modern contraceptives—mostly injectables, implants, pills, and IUDs.
Breast cancer is Kenya’s most diagnosed cancer, accounting for 16% of all new cancer cases. The disease often strikes women between 35 and 50 years, with many cases detected at late stages.
Risk depends on duration and type
The study found that women who had ever used hormonal contraceptives had a 24% higher relative risk of developing breast cancer compared with those who never used them.
Risk also rose with longer use: women who used hormonal contraceptives for five to ten years had a 34% higher risk.
A related 2023 study by the University of Oxford, published in PLOS Medicine, reinforced these findings, showing a consistent small rise in breast cancer risk across all hormonal contraceptive methods—including pills, injections, implants, and hormonal IUDs.
However, experts emphasize that the absolute risk remains low and that hormonal contraceptives continue to offer substantial benefits such as reliable pregnancy prevention, menstrual regulation, acne treatment, and reduced risk of ovarian and endometrial cancers.
Call for informed decisions
Medical specialists are urging women not to panic but to make informed choices, especially those with a family history of breast cancer or BRCA gene mutations.
“Women should discuss the risks and benefits with their healthcare providers,” said a Nairobi-based oncologist. “Hormonal contraceptives remain among the safest and most effective options—but individual factors matter.”
Globally, breast cancer remains the leading cancer among women, with 2.3 million new cases and 670,000 deaths in 2022.
The World Health Organization warns that cases could rise by 40% by 2050 if current trends persist.
