- Women who have been through natural menopause have a higher risk of developing cancer, but only because they are older, which is a risk factor for cancer.
- Some cancer treatments may cause menopause or menopausal symptoms in women and menopausal-like symptoms in men.
- Postmenopausal combined hormone therapy may increase a woman’s risk of cancer.
Menopause does not cause cancer, but the risk of developing cancer increases as a woman ages. Therefore, women who have been through natural menopause are more likely to develop cancer because they are older. In addition, some cancer treatments can cause menopause and menopausal symptoms.
Menopause occurs when a woman’s ovaries have no more eggs. First, her menstrual cycle becomes irregular, and then it stops completely and her body starts making less of the hormones estrogen and progesterone. It generally begins during a woman's mid-40s or early- to mid-50s. However, it can also begin earlier if cancer treatment, such as surgery, chemotherapy, or hormonal therapy, has stopped the ovaries from working; this is called premature menopause.
The symptoms of menopause include hot flashes, night sweats, vaginal dryness, sleeplessness, decreased sex drive, and mood swings. Learn about managing menopausal symptoms .
Menopause and cancer risk
A woman who experienced menopause after age 55 has an increased risk of ovarian, breast, and uterine cancers. This risk is greater if a woman also began menstruating before age 12. This is because a woman who menstruates longer than normal during her life is exposed to more estrogen and has more ovulations. A longer exposure to estrogen increases a woman’s risk of uterine and breast cancers, and having a more ovulations increases a woman’s risk of ovarian cancer.
Cancer treatments that cause menopause or menopausal symptoms
Some cancer treatments may cause menopause or menopausal symptoms. Menopause caused by medical treatment is called medical (or surgical, depending on the treatment received) menopause. The symptoms of medical or surgical menopause may be worse because the decrease in hormones happens quickly. Even if cancer treatment does not cause menopause immediately, it still may cause menopause to start sooner.
The following cancer treatments may cause menopause:
Oophorectomy (surgical removal of the ovaries). This type of surgery is used to treat or prevent ovarian, uterine, and vaginal cancers. It causes menopause immediately because the main source (the ovaries) of estrogen and progesterone is removed.
Radiation therapy or chemotherapy. Radiation therapy to the pelvis and chemotherapy that damages the ovaries can cause early menopause. Menstrual periods may return for some younger woman after treatment, but women older than age 40 are less likely to have their menstrual periods return.
Hormonal therapy. Hormonal therapy or endocrine therapy is used to treat breast cancer that is estrogen receptor- and/or progesterone receptor-positive, meaning the cancer uses estrogen and/or progesterone to grow. Hormonal or anti-estrogen therapies include aromastase inhibitors such as anastrozole (Arimidex), letrozole (Femara), and exemestane (Aromasin), as well as the drug tamoxifen (Nolvadex, Soltamox).These drugs may also be used to lower the risk of breast cancer returning after treatment. In addition, tamoxifen and the drug raloxifene (Evista) may be used to lower the risk of developing breast cancer for women who have a higher risk of the disease. The side effects of these drugs are similar to the symptoms of menopause.
Women taking hormonal therapy who have not been through menopause may have lighter and fewer regular menstrual periods, or their menstrual periods may stop completely. A woman’s menstrual periods may come back after hormonal therapy ends, but this is less likely for women who are closer to their natural menopausal age. Menopausal symptoms may come back for women who have already reached menopause if they are receiving hormonal therapy, especially when they first start. How long these symptoms last varies, but the symptoms stop once hormonal therapy is finished.
Men with prostate cancer who receive hormonal therapy or have their testicles removed may also experience symptoms similar to menopause. These include hot flashes, irritability, decreased sex drive, fatigue, osteoporosis (thinning of the bones), and erectile dysfunction (inability to have an erection). Learn more about managing hormone deprivation symptoms in men .
Menopausal hormone therapy and cancer risk
The Women’s Health Initiative  study found that women taking combined hormone therapy (also called postmenopausal hormone therapy or hormone replacement therapy) to manage menopausal symptoms may have a higher risk of breast cancer. Combined hormone therapy is a combination of estrogen and progestin (a form of progesterone made in a laboratory). It is used to help women cope with menopausal symptoms and prevent osteoporosis. Hormone therapy with estrogen alone is only given to women who have had a hysterectomy (the removal of the uterus) because estrogen increases the risk of uterine cancer.
The Women’s Health Initiative also found that women taking combined hormone therapy had a higher risk of heart attack, stroke, and blood clots. However, they had a lower risk of colorectal cancer and bone fractures. Because of these risks, many doctors recommend that women do not take combined hormone therapy or only take low doses for a short time. Combined hormone therapy is not usually recommended for women with a history of breast cancer or those who have a higher risk of breast cancer.
Recent research also showed that women who received combined hormone therapy have a higher risk of dying of non-small cell lung cancer (NSCLC) if they develop the disease. However, woman in the study taking combined hormone therapy were not more likely to develop NSCLC than women who were not taking combined hormone therapy. The study also showed that the risk of dying from lung cancer was higher for women with NSCLC who smoke and take combined hormone therapy.
Research on combined hormone therapy is controversial and ongoing. The risks and benefits of the treatment are different for each woman. If you are considering hormone therapy for menopausal symptoms, it is important to talk with your doctor about your symptoms, medical history, and your options for relieving the symptoms, including the risks and benefits and how long you should take hormone therapy.