How Hormones Can Affect Gynecological Cancer Risk: What Women Should Know

If you’re wondering whether the hormones in birth control, hormone replacement therapy, or even your natural monthly cycle could affect your cancer risk, you’re not alone. It’s a common concern, and the relationship between hormones and gynecological cancers is real — but it’s also more nuanced than many people realize.

Hormones, especially estrogen and progesterone, are central to women’s health and reproductive cycles. In a recent webinar presentation to raise awareness, Eleftheria Kalogera, M.D., a gynecologic oncologist at Baptist Health Miami Cancer Institute, explored how hormones interact with gynecologic cancers — and what women should know. 

“There are very different considerations, and it can be very unique in every individual’s circumstances,” Dr. Kalogera says. “There are some risk factors that we cannot change, but there may be some that we could potentially change.”

The most important thing is to have open discussions with your healthcare provider about your individual risk factors, including your family history, reproductive history and lifestyle factors, Dr. Kalogera says. Regular screening and yearly gynecological visits remain your best protection.

How Estrogen Affects Cancer Risk

Estrogen is a natural hormone that helps regulate menstrual cycles, fertility and bone health. But in certain cancers, estrogen can act like “fuel,” stimulating abnormal cells to grow more quickly. This doesn’t mean estrogen alone causes cancer. Instead, when cells are already abnormal, estrogen exposure can spark them to grow and spread, Dr. Kalogera explains.

“The actual estrogen, the hormone, can stimulate cancer growth,” she says. “It doesn’t mean that the estrogen is the only factor. Usually, the development of the cancer is a very complex process, but in this process, the presence of hormones — and specifically estrogen — can be a potent stimulant for the growth and the spread of the cancer.”

The relationships are complex, and many factors beyond hormones affect cancer risk, including genetics, lifestyle and environmental factors, Dr. Kalogera notes.

Uterine Cancer: The Strongest Hormone Link

Of all gynecological cancers, uterine cancer, also called endometrial cancer, has the clearest connection to hormones. The lining of the uterus, called the endometrium, is designed to thicken each month in response to estrogen, then shed during menstruation when progesterone levels drop. When estrogen stimulates this lining month after month without the balancing effect of progesterone, abnormal growth can occur.

Factors that can influence risk include:

·       Starting your period very early, before age 12, or going through menopause late, after age 55.

·       Irregular periods or not ovulating regularly, which means less progesterone production.

·       Being significantly overweight, because fat tissue actually produces estrogen.

·       Taking estrogen alone (without progesterone) for menopausal symptoms.

Ovarian Cancer: A More Complex Picture

Ovarian cancer’s relationship with hormones is less straightforward than uterine cancer, but there are still important patterns.

Interestingly, each pregnancy reduces ovarian cancer risk by about 10-15 percent, and each year of breastfeeding provides additional protection. Birth control pills also significantly lower ovarian cancer risk and using them for five years can reduce your risk by about 25-30 percent.

Cervical Cancer: When Hormones Meet HPV

Cervical cancer is primarily caused by persistent infection with certain types of human papillomavirus (HPV), not hormones. However, hormones can influence whether an HPV infection progresses to cancer, Dr. Kalogera says.

This is why regular Pap smears are so important, especially for women who use hormonal birth control long-term. The good news is that cervical cancer is highly preventable through screening and HPV vaccination.

Birth Control Pills: More Protection Than Risk

One of the most reassuring findings in cancer research is that birth control pills actually prevent more cancers than they might cause, Dr. Kalogera says. While there’s a small increased risk of cervical cancer (in women with HPV) and in breast cancer, the pill significantly reduces the risk of both ovarian and uterine cancers.

The ovarian cancer protection is particularly valuable because this cancer is often diagnosed at advanced stages and is difficult to treat. The uterine cancer protection is substantial and long-lasting. Overall, women who use birth control pills have lower rates of cancer-related deaths than women who don’t.

Hormone Replacement Therapy (HRT)

HRT is commonly prescribed to relieve symptoms of menopause, such as hot flashes, night sweats and bone loss. But many women wonder if HRT increases cancer risk.

Dr. Kalogera says the answer is nuanced. HRT remains a powerful option for many women. The small additional risk of cancer should be weighed against the significant quality-of-life benefits, and decisions should be made in consultation with a knowledgeable physician.

“Hormone replacement therapy has a place for certain patients in the hands of an experienced and knowledgeable physician,” she says. “With counseling and the right approach, it is a very powerful intervention for women.”

If a woman still has her uterus, taking estrogen alone does increase the risk of endometrial cancer because estrogen stimulates the uterine lining without the balancing effect of progesterone. It may also cause a very small increase in ovarian cancer risk — about one additional case per 1,000 women using estrogen-only HRT for more than five years, Dr. Kalogera says.

Combined HRT — adding progesterone — offers a protective effect. In fact, studies suggest combined therapy may lower the risk of endometrial cancer.

What This Means for Your Health Decisions

Understanding these hormone-cancer connections doesn’t mean you should fear your natural hormones or avoid all hormonal medications, Dr. Kalogera says. Instead, this knowledge should help you make informed decisions with your gynecologist or primary care provider.

Dr. Kalogera emphasizes that while not all gynecologic cancers can be prevented, many risks can be reduced with these steps:

·       Regular gynecologic care: Pap tests, HPV testing and routine checkups are critical for early detection at every age.

·       HPV vaccination: For everyone under the age of 26, and for some people up to age 45, HPV vaccination strongly reduces risk of cervical, vaginal and vulvar cancers. It also is protective in mouth and throat cancer and other cancers.

·       Maintaining a healthy lifestyle: Achieving a healthy weight, staying active, and not smoking lower overall cancer risk.

·       Genetic testing: Depending on your family history, genetic testing can help identify inherited risks, such as BRCA mutations or Lynch syndrome.

Symptoms of gynecologic cancers can be vague — bloating, abnormal bleeding, pelvic pain or pressure, fatigue, back pain. Don’t underestimate the importance of anything out of the ordinary. Dr. Kalogera’s advice: “If you feel something that doesn’t feel right, say something to your healthcare provider. And if you don’t feel heard or get an answer that satisfies you, say something to someone else. Seek out your gynecologist, who can do some investigation to make sure there’s not anything bad going on.”

Eleftheria Kalogera, M.D., a gynecologic oncologist at Baptist Health Miami Cancer Institute