Is There a Link Between Hysterectomy and Breast Cancer?

The relationship between hysterectomy and breast cancer is not a simple yes-or-no story. Whether the surgery raises, lowers, or has no meaningful effect on breast cancer risk depends on a few critical details: whether the ovaries are also removed, what kind of hormone therapy follows, and how old a woman is when the surgery happens. A recent meta-analysis found that hysterectomy combined with bilateral oophorectomy (removal of both ovaries) was associated with roughly a 16% lower risk of breast cancer, while hysterectomy alone showed about a 13% reduction. But at least one large prospective study found the opposite for hysterectomy alone, pointing toward a small increase in risk. The disagreement between studies reveals how tangled this question really is.

The Overall Picture From Research

A 2025 meta-analysis pooling data from multiple studies estimated that hysterectomy combined with oophorectomy lowered breast cancer risk by about 16%, standalone hysterectomy by about 13%, and bilateral oophorectomy alone by roughly 19%.¹ That sounds relatively straightforward, but not every study fits neatly into this picture. In a large racially diverse prospective cohort, hysterectomy without ovary removal was associated with a 12% higher breast cancer incidence compared to women who had no surgery at all, while bilateral oophorectomy was associated with a modest reduction.² Meanwhile, an earlier case-control study found hysterectomy with ovarian conservation was associated with about a 17% lower risk of breast cancer.³

Why do the studies disagree? The populations differ, the follow-up periods differ, and the way researchers account for hormone therapy use and other confounders varies. Some studies compare hysterectomy patients to the general population, while others compare different surgical groups against each other. The meta-analysis attempts to reconcile these discrepancies, and its pooled estimate lands on a modest reduction. But the honest answer is that for hysterectomy without ovary removal, the evidence is genuinely mixed, and the effect, in whichever direction it falls, is likely small.

Why Ovary Removal Is the Pivotal Variable

The ovaries are the body’s primary source of estrogen and progesterone during the reproductive years, and many breast cancers are fueled by these hormones. Removing both ovaries before natural menopause abruptly cuts off that hormonal supply. This is the main mechanism by which gynecologic surgery can reduce breast cancer risk.⁴ The younger a woman is when the ovaries come out, the more years of hormonal exposure are eliminated, and the larger the apparent reduction in breast cancer risk.

One study of premenopausal women found that bilateral oophorectomy before age 50 was associated with roughly a 50% reduction in breast cancer risk compared to the general population, with the benefit becoming visible within a decade of surgery. Oophorectomy performed after age 50, or after natural menopause had already occurred, showed no comparable reduction.⁵ A nationwide Danish cohort study echoed this pattern: women who had bilateral oophorectomy before age 45 had a roughly 22% lower breast cancer risk compared to women who had hysterectomy alone, while women over 50 at surgery did not see the same benefit.⁶

This age effect makes biological sense. By the time a woman reaches her early fifties, the ovaries have already begun winding down estrogen production through natural menopause. Removing them at that point does not eliminate many additional years of hormone exposure. Before menopause, however, each year without functioning ovaries is a year without high circulating estrogen stimulating breast tissue.

How Hysterectomy Alone Can Affect the Ovaries Anyway

Even when a surgeon carefully preserves both ovaries during a hysterectomy, the remaining ovaries do not always keep working as they did before. A study following women over several years after hysterectomy found they were nearly twice as likely to experience ovarian failure compared to women with intact uteruses. About 15% of women who had a hysterectomy experienced ovarian failure within four years, compared to 8% in the control group.⁷ Women who had one ovary removed along with the uterus faced an even higher risk.

The likely explanation involves blood supply. The uterus and ovaries share overlapping blood vessels, and removing the uterus can compromise blood flow to the ovaries even if the ovaries themselves are untouched. Research has shown that ovarian blood flow measurements change after hysterectomy, with vascular resistance shifting in ways consistent with reduced perfusion.⁸ This matters for the breast cancer question because if hysterectomy inadvertently pushes the ovaries toward earlier failure, it could partly mimic the hormonal effects of oophorectomy, just less predictably and less completely. It might help explain why some studies find a modest breast cancer risk reduction even with ovarian conservation.

The Hormone Therapy Complication

Many women who have a hysterectomy, especially those who also lose their ovaries before natural menopause, take hormone therapy to manage the sudden onset of menopausal symptoms. The type of hormone therapy matters enormously for breast cancer risk, and it often gets lumped together in ways that obscure the real picture.

Women who have had a hysterectomy can take estrogen alone because they no longer need a progestin to protect the uterine lining. This distinction turns out to be critical. The Women’s Health Initiative randomized trial found that estrogen alone actually lowered breast cancer risk during the treatment period, with a hazard ratio below 1 that persisted into the early years after stopping. Combined estrogen-plus-progestin therapy, by contrast, was associated with increased breast cancer risk that climbed steadily with years of use.⁹

A large meta-analysis of worldwide data reinforced this gap. Among current users of estrogen-progestin therapy, breast cancer risk was roughly doubled compared to non-users after five to fourteen years. Estrogen-only users also had elevated risk, but it was considerably smaller. After stopping either type, some excess risk persisted for more than a decade, with the magnitude depending on how long the therapy had been used.¹⁰ Earlier research had similarly shown that adding a progestin to hormone therapy markedly enhanced breast cancer risk relative to estrogen alone.¹¹

In the large prospective cohort study of hysterectomy and oophorectomy, women who had bilateral oophorectomy and then took estrogen alone had a lower breast cancer risk than women who had no surgery at all. But women who had hysterectomy alone and used combined estrogen-plus-progestin therapy had about a 25% higher risk.² This means the same surgery can appear protective or harmful depending on what medication follows it.

Estrogen After Oophorectomy in Practice

For women who have their ovaries removed before natural menopause, hormone therapy is not just about comfort. Premature loss of ovarian hormones is associated with increased risks of osteoporosis and cardiovascular disease, so many women are advised to take replacement hormones at least until the age when they would have reached menopause naturally. The breast cancer implications of that therapy are nuanced.

A study of women who had both uterus and ovaries removed found that current estrogen use was associated with a modest increase in breast cancer risk overall, but women who had the surgery before age 40 still had roughly a 25-30% lower breast cancer risk regardless of whether they used estrogen or not.¹² In other words, the protective effect of very early ovary removal was large enough that taking estrogen afterward did not erase it entirely.

Among women with BRCA mutations who had risk-reducing surgery, each year of estrogen-only hormone therapy was associated with a small reduction in breast cancer risk for BRCA1 carriers specifically. Combined estrogen-progestin therapy did not show a significant association with increased risk in this group after adjusting for other factors, though long-term use of combined therapy in women who had surgery before age 45 hinted at elevated risk.¹³ The picture differs enough between BRCA1 and BRCA2 carriers that blanket recommendations are hard to make.

BRCA Mutation Carriers

For women who carry BRCA1 or BRCA2 mutations, the stakes of gynecologic surgery are higher because their baseline breast cancer risk is already substantially elevated. Risk-reducing salpingo-oophorectomy, which removes both ovaries and fallopian tubes, is one of the most studied interventions in this population.

A systematic review and meta-analysis found that this surgery lowered breast cancer risk by roughly 37% in BRCA1 carriers and about 49% in BRCA2 carriers. The benefit was stronger in younger women: BRCA2 carriers who had the surgery at a younger age saw about a 78% reduction, while younger BRCA1 carriers saw roughly a 52% reduction.¹⁴ Another study found the benefit was strongest in the first five years after surgery, with the protective effect waning over time, particularly in BRCA2 carriers where the long-term benefit largely disappeared.¹⁵

An earlier landmark study that helped establish this approach found that breast cancer or BRCA-related gynecologic cancer was diagnosed far less often among women who had preventive oophorectomy than among those who chose surveillance.¹⁶ Taken together, the evidence is strong enough that risk-reducing salpingo-oophorectomy is widely recommended for BRCA carriers, though the timing and trade-offs require individualized discussion.

Do the Conditions Leading to Hysterectomy Matter?

Hysterectomy is not performed randomly. Women have the surgery for specific reasons, most commonly uterine fibroids, endometriosis, abnormal bleeding, or uterine prolapse. Some of those underlying conditions share hormonal risk factors with breast cancer, which creates a confounding problem researchers have to untangle.

Uterine fibroids, for instance, are estrogen-dependent growths that share several risk factors with breast cancer, including obesity, early menarche, and alcohol use. Research has found a strong association between the two conditions. However, this link likely reflects common underlying drivers rather than one causing the other. Even after adjusting for known shared risk factors, some residual association remains, suggesting that unidentified environmental or genetic factors may contribute to both.¹⁷ Research using national health databases has similarly noted the hormone-mediated connection: fibroids depend on ovarian estrogen and progesterone for growth, and most shrink after menopause, mirroring the hormone sensitivity seen in many breast cancers.¹⁸

This means that women who are selected for hysterectomy because of fibroids may already have a somewhat different hormonal profile than the average woman. Studies that compare hysterectomy patients to the general population without accounting for this selection can conflate the effect of the surgery itself with the effect of the underlying condition. It is one reason researchers are cautious about interpreting modest risk changes in either direction.

Screening Bias in the Studies

There is another wrinkle that complicates the research. Women who take hormone therapy after surgery tend to see their doctors more regularly and get more mammograms than women who do not. More mammograms mean more breast cancers detected, even if those cancers would eventually have been found anyway. Some older observational studies that reported modest breast cancer increases with estrogen use did not adequately account for this screening difference.¹⁹

Randomized trials are less susceptible to this problem because mammography schedules are typically built into the study protocol. The Women’s Health Initiative’s estrogen-alone trial, for example, had similar screening rates in both groups, and the reduction in breast cancer associated with estrogen use was accompanied by a reduction in breast cancer deaths, a finding that argues against the results being an artifact of screening differences.²⁰

Does the Type of Breast Cancer Matter?

Most of the protective effect you would expect from cutting off estrogen and progesterone would logically apply to hormone-receptor-positive breast cancers, the types that have receptors for these hormones and use them to grow. But the evidence is somewhat surprising. One study of Black and White women in the Carolina Breast Cancer Study found that premenopausal hysterectomy, even without ovary removal, was associated with reduced risk of both hormone-receptor-positive and hormone-receptor-negative breast cancers, with no difference by race.²¹ That finding is harder to explain through hormone withdrawal alone and hints that other mechanisms may be at play, though it comes from a single study and needs replication.

Breast Density as a Visible Signal

Breast density is one of the strongest independent risk factors for breast cancer, and it responds to hormonal changes. If oophorectomy works partly by reducing circulating hormones, you would expect breast tissue to become less dense after surgery. That is exactly what researchers have found. In BRCA mutation carriers, volumetric breast density dropped substantially after oophorectomy, from a median of about 12.5% to 10.2%, driven by a reduction in the fibroglandular tissue component. The decrease was greatest in women between ages 40 and 50.²²

A more recent study quantified this more precisely, finding that breast density dropped by an average of about 6% in women who underwent risk-reducing salpingo-oophorectomy between mammograms, compared to less than 1% in women who did not. The density decrease was driven primarily by BRCA2 carriers. Using hormone therapy after surgery partially blunted this density decline.²³ This density reduction may partly explain the breast cancer risk reduction seen after oophorectomy and provides a visible, measurable biomarker that surgery has changed the breast’s hormonal environment.

The Trade-Offs Beyond Breast Cancer

Focusing only on breast cancer risk gives an incomplete picture of what these surgeries mean for long-term health. The Nurses’ Health Study, one of the largest and longest-running cohort studies, found that oophorectomy at the time of hysterectomy did reduce the risk of breast cancer and ovarian cancer. But it came with costs. Overall cancer mortality went up, as did the risk of death from coronary heart disease. When everything was added together, women who had their ovaries removed at hysterectomy had a 12% higher risk of death from any cause compared to women who kept their ovaries.²⁴

This is why the decision about ovary removal at hysterectomy is not simply a cancer math problem. Heart disease kills more women than all cancers combined, and the cardiovascular protection provided by premenopausal ovarian hormones is substantial. For women at average cancer risk, preserving the ovaries at hysterectomy may offer a better balance of long-term outcomes even though it means a somewhat higher breast cancer risk than removal would provide. For women at elevated genetic risk, the calculation shifts. Research into women’s preferences has shown that when presented with personalized risk scenarios, women tend to weigh ovarian cancer risk reduction heavily in their decision, while increases in osteoporosis and heart disease risk also matter but are given somewhat less weight.²⁵ The answers are individual, which is exactly what makes them difficult.