Published in Acta Obstetricia et Gynecologica Scandinavica, the study confirms a clear inverse association between oral contraceptive (OC) use and the risk of endometrial cancer (EMC).
Women who had ever used OCs had a 39% lower chance of developing EMC compared to never-users.
The protective association between the use of OCs and the risk of EMC has proven to be stronger with duration of use: women using OCs for less than five years had a 34% lower risk, those using them for five or more years had a 61% lower risk, and the strongest benefit – a 69% reduction – was observed in women who used OCs for at least ten years.
When the analysis was restricted to users of combined oral contraceptives (COCs), the protective association was even more pronounced, with a 54% reduction in the odds of endometrial cancer compared to non-users.
“The use of oral contraceptives, which regulate hormone levels, appears to reduce the proliferation of endometrial cells, potentially lowering mutation rates and long-term cancer risk,” explains Dr. András Harajka, a PhD student at Semmelweis University’s Centre for Translational Medicine, and the first author of the study.
The systematic review screened 56 international studies, with 25 studies also eligible for meta-analysis. The pooled data included nearly 10,000 women diagnosed with EMC.
Endometrial cancer risk is over eight times higher in women aged 35–70 than in younger females, and obesity (BMI over 30) has been linked to nearly triple the odds. While parity may reduce endometrial cancer risk by up to 31%, late menopause may be linked to doubling it.
Endometrial cancer is now the most common gynaecological malignancy in high-income countries, with more than 417,000 new cases reported globally in 2020 alone, the research warns. The World Health Organization projects a 49% increase in EMC cases by 2050. These rising trends have been linked to factors such as aging, obesity, and hormonal influences. Prior studies have shown that hormonal factors – particularly the roles of oestrogen and progesterone – play a central role in EMC risk.
Co-author Dr. Nándor Ács, also head of the Department of Obstetrics and Gynaecology at Semmelweis University, added: “Our findings provide robust and up-to-date evidence that oral contraceptive use is significantly associated with lower risk of endometrial cancer, particularly with longer use. This is an important consideration for patients and clinicians when discussing contraceptive options.”
The researchers caution that, while oral contraceptives used by more than 150 million worldwide offer significant protective benefits, they can also carry side effects including mood changes, nausea, and, in rare cases, an increased risk of blood clots or stroke.
Common symptoms of endometrial cancer include abnormal vaginal bleeding (especially after menopause), pelvic pain, and unusual discharge. Women experiencing any of these signs should seek medical advice promptly. While there is no routine screening test for endometrial cancer, early diagnosis is often possible through pelvic examination, transvaginal ultrasound, and endometrial biopsy.
Photo: Boglarka Zellei, Attila Kovacs – Semmelweis University; Cover photo and illustration: Johnstocker – Envato Elements
