Does Birth Control Pill Use Reduce Ovarian Cancer Risk?

A new analysis of health records suggests that oral contraceptive use and a higher number of live births reduce ovarian cancer risk.

On January 6, 2025, The International Journal of Gynecological Cancer published the study, about which Australia's Dr. Iqbal Madakkatel said: "Our large, hypothesis-free machine-learning study suggests that ovarian cancer risk is at least partly modifiable and that predictive blood tests could be developed to detect it at an early stage."

Study Details

The research analyzed 222 thousand women in the UK Biobank, examining 2920 exposures and identifying 1441 ovarian cancer cases over 12.6 years.

The analysis used the 87 top-ranked predictors, representing the top 3%. They covered baseline and personal characteristics, female-specific factors, sociodemographic circumstances, lifestyle and environment, cognitive and psychosocial factors, physical measurements, health and medical history, and biomarkers .

Any woman who has used oral contraceptives for a total of 5 years reduces her ovarian cancer risk by approximately 50%. Numerous meta-analyses support their protective effect.

Each month, ovulation causes an inflammatory reaction or process on the ovarian surface, and preventing it may explain the reduction in ovarian cancer. Copper intrauterine devices (IUDs) do not prevent ovulation, while hormonal IUDs may partially suppress it in some women, although this is not their main mechanism. Evidence on whether IUDs are as effective as oral contraceptives is therefore conflicting.

Which Ovarian Cancer Risk Factors Can Be Modified?

Strong risk factors include family history and genetic mutations such as BRCA1 and BRCA2. Other nonmodifiable factors include early menstruation or late menopause, allowing more ovulations, and endometriosis. Known modifiable factors mainly involve reducing ovulation, including more pregnancies and breastfeeding. In this study, participants with at least two live births had a likelihood of ovarian cancer 39% lower than those who had never given birth.

What Makes Ovarian Cancer Screening and Detection Difficult?

Women diagnosed with stage one ovarian cancer have excellent 5-year survival above 90%, but only approximately 17% of cases are detected this early. Symptoms are often vague, including abdominal bloating, discomfort, and poor appetite, prompting initial visits to primary care. Ovarian cancer behaves differently from most other cancers, however. Breast and colon cancers begin at one point and grow outward, whereas even a small ovarian tumor can scatter through the abdomen like dandelion seeds because of the ovaries' location, remaining undetected for a long time.

What New Evidence Does This Study Provide?

Earlier studies produced conflicting evidence about height and weight, but this study found positive associations for both. Each additional standard-deviation increase in height was associated with a 13% higher risk. Measures of adiposity, such as body fat percentage, increased cancer likelihood by 14% to 28%, depending on the measure.

Could Biomarkers Offer Future Screening Opportunities?

Ovarian cancer screening has long been a holy grail for researchers, but decades of work have not produced a successful screening test. The way this cancer develops makes the challenge complex. Even ultrasound screening every six months has not improved early detection or survival.

Previous failures combining tumor markers with ultrasound also deserve attention. These blood biomarkers are exciting because testing is simple, but other conditions may change the values, and they are not specific to ovarian cancer. Choosing a testing interval is another challenge: "Would you perform laboratory tests every month, every 3 months, or every 6 months?"

The researchers also examined factors such as glutamine and alanine . More attention should be paid to cancer cell metabolism and the tumor microenvironment, which may help develop early-detection or screening tests. Researchers hope to find a way to detect this disease early.

Associations between blood biomarkers and ovarian cancer risk may illuminate tumor development mechanisms and support predictive blood tests. Higher aspartate aminotransferase and alanine aminotransferase levels reduced ovarian cancer likelihood by 11%. A higher neutrophil percentage slightly increased risk (OR, 1.08), while higher total serum protein was associated with lower risk (OR, 0.86).

These findings may improve understanding of risk factors and protective strategies and offer new routes to early detection. Such advances provide valuable information for healthcare professionals and the public.