Estrogen may reduce or increase ovarian cancer risk, depending on the source. Oral contraceptives lower ovarian cancer risk, while high endogenous estrogen and menopausal hormone therapy may boost it.
Ovarian cancer starts in the ovaries, the female reproductive glands that make eggs. An estimated 20,890 women in the United States will receive a diagnosis of this type of cancer in 2025.
Several factors are known to either increase or decrease your risk of ovarian cancer. As such, you may be curious whether estrogen can reduce the risk of ovarian cancer.
The effect that estrogen has on ovarian cancer risk is a bit nuanced. While some estrogen sources, such as oral contraceptives, are protective, others can increase risk. Continue reading to learn more.
The connection between estrogen and the risk of ovarian cancer is a complex topic. In the following sections, we’ll examine how different estrogen sources can affect your risk.
Endogenous estrogen
Endogenous estrogen refers to estrogen that’s made naturally in your body. The ovaries are your body’s main producers of estrogen prior to menopause. Your adrenal glands also make small amounts of estrogen.
Some studies have found that higher levels of endogenous estrogen are associated with a higher risk of ovarian cancer. This may have to do with the fact that there’s evidence supporting estrogen’s role in regulating the growth and invasiveness of ovarian cancer cells.
A 2022 analysis of data from the UK Biobank found that high endogenous estradiol may encourage the development of ovarian cancer. Estradiol is the most common type of estrogen your body makes before menopause.
Results from another
Oral contraceptives
Oral contraceptives, which contain a synthetic form of estrogen, have long been known to protect against ovarian cancer.
According to the National Cancer Institute (NCI), research has found that women who have used oral contraceptives at any point in their lives have a
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Further, additional research has found that longer use of oral contraceptives is also protective in people with mutations in BRCA1, which is known to boost ovarian cancer risk.
Experts aren’t exactly sure why oral contraceptives reduce ovarian cancer risk. According to the
Hormone replacement therapy
Hormone replacement therapy (HRT) is prescribed to women to help reduce symptoms associated with menopause. It may be estrogen-only or an estrogen-progesterone combination.
HRT use after menopause is a
For example, a 2016 study found that current or recent use of estrogen-only HRT was linked to a higher risk of serous ovarian cancer and endometroid ovarian cancer. The risk of ovarian cancer increased the longer the HRT was used.
A 2024 study followed postmenopausal women using HRT for 20 years. Compared to placebo, estrogen-only HRT significantly boosted ovarian cancer risk.
However, estrogen-progesterone HRT was not associated with an increased risk of ovarian cancer.
Another 2020 study also observed that estrogen-progesterone HRT wasn’t linked to overall ovarian cancer risk. In fact, it was found that this type of HRT was linked to a lower risk of mucinous ovarian cancer.
It’s possible that adding progesterone to HRT may reduce the effects that estrogen has on ovarian cancer risk. Overall, more research into this topic is needed.
There are also several other risk factors for ovarian cancer. These include:
- Age: Older age boosts ovarian cancer risk. This cancer is rare in women under the age of 40. About half of the women diagnosed with ovarian cancer are
63 or older . - Reproductive factors: Women who’ve never had a full-term pregnancy are at a higher risk of ovarian cancer. You may also be at an increased risk if you had your first child
after age 35 . - Obesity: While the reasons why aren’t clear, ovarian cancer is one of
13 cancer types linked to obesity. - Family history: Ovarian cancer can run in families due to the fact that certain genetic changes increase risk. Because these changes are also often linked to breast and colorectal cancer, having a family history of these cancers also boosts your risk of ovarian cancer.
- Personal history: A personal history of breast cancer increases your risk of ovarian cancer. This is largely due to
overlapping reproductive and genetic risk factors. - Smoking: Smoking is linked to a higher risk of
mucinous ovarian cancer but not other types. - Fertility treatments: Fertility treatments may be associated with a higher risk of ovarian cancer. However, the overall risk level is believed to be small.
It’s important to point out that having risk factors for ovarian cancer doesn’t mean you’re certain to develop it.
Having risk factors simply means that you’re at a higher risk than those without risk factors. You can use this information to take steps to prevent ovarian cancer or to detect it early.
A few factors can also lower one’s risk of ovarian cancer. These may be described as protective factors.
One protective factor that we’ve already discussed is oral contraceptives. Compared to women who’ve never used oral contraceptives, those who’ve used them for 5 years or longer have about a
Other protective factors for ovarian cancer
- giving birth
- choosing to breastfeed your child
- having a previous tubal ligation or hysterectomy
Having both ovaries and fallopian tubes removed also protects against ovarian cancer. After consulting with a doctor, women with a high risk of ovarian cancer may consider this surgery in order to reduce their risk.
Estrogen has a pretty nuanced role in ovarian cancer risk. The use of high endogenous estrogen and estrogen-only HRT increases the risk of ovarian cancer. Meanwhile, oral contraceptive use decreases risk.
There are also other risk factors for ovarian cancer. These include older age, family history, and obesity.
Not everyone with risk factors will go on to have ovarian cancer. However, if you do have risk factors, have an open conversation with your doctor about the steps you can take to reduce your risk.