Ovarian cancer has no single cause, but a combination of genetic, hormonal, reproductive, and lifestyle factors can raise or lower your risk. The median age at diagnosis is 63, and the overall rate is about 10.4 new cases per 100,000 women per year. Nearly half of all diagnoses occur in women between 55 and 74. Understanding what drives risk can help you have more informed conversations about screening and prevention.
Inherited Gene Mutations
The strongest known risk factors for ovarian cancer are inherited mutations in the BRCA1 and BRCA2 genes. Women who carry a harmful BRCA1 change have a 39% to 58% lifetime risk of developing ovarian cancer. For BRCA2 carriers, the lifetime risk is 13% to 29%. Compare that to the general population risk of roughly 1.3%, and the scale of these mutations becomes clear.
Lynch syndrome, caused by inherited changes in DNA repair genes, also increases ovarian cancer risk. The degree depends on which gene is affected. Changes in MSH2 carry an 8% to 38% lifetime risk, while MLH1 changes carry a 4% to 20% risk. Two other Lynch-associated genes, MSH6 and PMS2, appear to confer little to no meaningful increase beyond the baseline population risk. If you have a strong family history of ovarian, uterine, or colorectal cancer, genetic counseling can help determine whether testing makes sense.
How Ovulation Itself Creates Risk
One of the most well-supported theories in ovarian cancer research centers on ovulation. Each time an egg is released, the surface of the ovary ruptures and must repair itself. That repair process requires cells to divide rapidly, and over decades of monthly ovulation, the accumulated cell divisions increase the chance of a DNA copying error that could lead to cancer. Women with higher lifetime ovulation counts, meaning more total menstrual cycles, face greater risk.
The process closely resembles an inflammatory reaction. Immune cells flood the area, and the body produces signaling molecules that trigger tissue remodeling. This chronic, low-grade inflammation compounds the damage from repeated surface rupture. It’s one reason that anything reducing total lifetime ovulations, such as pregnancy, breastfeeding, or oral contraceptives, is associated with lower risk.
Reproductive Factors That Shift Risk
Because ovulation frequency matters so much, reproductive history plays a direct role. Women who have never been pregnant tend to have a higher risk than those who have, simply because pregnancy pauses ovulation for nine months. Breastfeeding extends that pause further.
Oral contraceptives are one of the most consistent protective factors identified in research. Women who have ever used birth control pills have a 30% to 50% lower risk of ovarian cancer compared to women who have never used them. The protection increases with longer use and persists for years after stopping. This reduction is largely attributed to the suppression of ovulation during pill use.
Surgical removal of the fallopian tubes also lowers risk. Data from the Nurses’ Health Studies found that women who had undergone tubal ligation had a 24% lower risk of ovarian cancer. There is growing evidence that many of the most common and aggressive ovarian cancers actually originate in the fallopian tubes rather than the ovaries themselves. This is why some gynecologists now recommend removing the fallopian tubes during unrelated pelvic surgeries like hysterectomy, a strategy called opportunistic salpingectomy. It reduces risk but does not eliminate it entirely.
Hormone Replacement Therapy
Menopausal hormone therapy increases ovarian cancer risk, and the effect begins earlier than many women expect. A large meta-analysis of 52 studies found that even fewer than five years of use raised risk by about 43% among current users. The increase applied to both estrogen-only and combined estrogen-progestagen formulations.
Risk does decline after stopping, but slowly. Even a decade after discontinuing long-term hormone therapy, women still had a 25% elevated risk of the two most common ovarian cancer subtypes, serous and endometrioid. In practical terms, the researchers estimated that for every 1,000 women who use hormone therapy for five years starting around age 50, there would be roughly one additional ovarian cancer diagnosis. That’s a small absolute number, but it’s worth weighing against the benefits of hormone therapy for managing menopausal symptoms.
Endometriosis
Endometriosis, a condition where tissue similar to the uterine lining grows outside the uterus, is linked to specific subtypes of ovarian cancer. Women with endometriosis were 7.5 times more likely to develop type I ovarian cancers, which include clear cell and endometrioid subtypes. Those with the most severe forms of endometriosis, specifically deep infiltrating disease and ovarian endometriomas (cysts on the ovary), had the greatest risk: nearly 19 times higher for type I cancers and more than 9 times higher overall compared to women without endometriosis.
These are striking relative increases, but it’s important to keep context in mind. Ovarian cancer is uncommon to begin with, so even a ninefold increase in a small baseline risk still translates to a relatively low absolute chance. Still, women with severe endometriosis benefit from awareness and ongoing monitoring.
Body Weight
The relationship between weight and ovarian cancer is more nuanced than for many other cancers. A recent study tracking weight patterns across adulthood found that women who maintained a normal weight throughout life and those who gradually moved from normal weight to overweight had similar ovarian cancer risk. However, women who followed a trajectory from overweight in early adulthood to obese later in life showed a trend toward 45% higher risk, though the finding did not reach full statistical certainty. Excess body fat is thought to influence risk through hormonal changes, particularly higher circulating estrogen levels produced by fat tissue after menopause.
Talcum Powder
The question of whether talcum powder applied to the genital area causes ovarian cancer remains genuinely unresolved. The theory is that powder particles could travel through the reproductive tract to the ovaries and trigger chronic inflammation. Some older studies, particularly those relying on women’s recall of past talc use, found a small increase in risk. But prospective studies, which track women forward in time and avoid memory bias, have generally not found a significant overall increase.
Meta-analyses combining results across studies have also produced mixed conclusions. One analysis of cohort studies alone showed no increased risk, while another including both cohort and case-control data found a link with frequent use (at least twice a week). The American Cancer Society notes that if an increase exists for any individual woman, it is likely very small. Because ovarian cancer is relatively rare, even large studies may lack the statistical power to detect a modest effect.
Age and Who Is Most Affected
Ovarian cancer is predominantly a disease of older women. Nearly 70% of cases are diagnosed in women 55 and older. Only about 6% occur in women under 35. Risk climbs steadily through midlife, peaks between 55 and 74, and remains elevated into the 80s. This age pattern aligns with the cumulative nature of the risk factors described above: decades of ovulation, prolonged hormone exposure, and the slow accumulation of genetic damage over time.
There is no reliable screening test for ovarian cancer in the general population. Neither blood tests nor ultrasound have proven effective at catching it early enough to reduce deaths in average-risk women. For those with inherited gene mutations or strong family histories, more intensive surveillance and risk-reducing surgeries are options worth discussing with a specialist.