Menopause can bring about a lot more than just the symptoms and changes you're familiar with, like the end of your menstrual cycle and the onset of hot flashes. It can also be accompanied by some more serious conditions, including sleep disorders and increased stress. And while the transition itself doesn’t cause breast cancer, the likelihood of developing it does increase with age.
But just how much? While younger women are more likely to develop certain aggressive forms of breast cancer, research suggests that breast cancer risk increases by about 3 percent for each additional year of age at menopause, likely due in part to longer exposure to reproductive hormones.
We consulted with experts to understand how breast cancer can impact a woman differently before and after menopause.
Why does menopause status matter with breast cancer?
There are several factors that doctors take into account when diagnosing breast cancer, including age and, when determining treatment, whether or not a patient has gone through menopause.
The average age of reaching menopause in the U.S. is 51, but going through it later in life — particularly after age 55 — is associated with a higher risk of breast cancer.
Studies show higher blood levels of estradiol (the form of estrogen made mainly by the ovaries) are linked to an increased risk of breast cancer in postmenopausal women. But Matthew Goetz, MD, says the hormonal changes of menopause itself are responsible for developing cancer.
“The number of menstrual cycles that women go through seems to be longer perhaps than they used to be,” Dr. Goetz, an oncologist at The Mayo Clinic, tells Katie Couric Media. “But we don't see evidence necessarily that changes or fluctuations in hormones that are occurring with menopause are necessarily driving the development of breast cancer.”
That said, certain aggressive forms of breast cancer are more common in younger, premenopausal women. According to the Cleveland Clinic, breast cancer can also be more challenging to detect in younger women because their breast tissue is generally denser, making abnormalities harder to spot on mammograms. Routine screening for women at average risk generally begins at age 40.
How does menopause affect breast cancer treatment?
Where you are in your reproductive journey can make a big difference when it comes to treatment. For instance, hormone receptor-positive breast cancers have estrogen or progesterone receptors, meaning hormone-blocking therapies can help prevent the cancer from growing. Menopausal status helps determine which treatments are appropriate. Aromatase inhibitors, which reduce estrogen production, are commonly used in postmenopausal women. They can also be used in premenopausal women when combined with ovarian suppression. Hormone receptor-negative breast cancers, on the other hand, don't respond to these treatments.
Why does breast cancer treatment trigger menopause?
Other cancer treatments, such as chemotherapy, can trigger menopause or intensify menopausal symptoms. Meghan Karuturi, MD, says this reaction often happens because the treatment “basically puts ovaries to sleep,” so they stop producing eggs and a woman will no longer have a monthly period. For younger women, this effect may be temporary, and menstruation can return months or even years after treatment. But chemotherapy-induced menopause can also be permanent, depending on factors including age and the type of treatment received. If a woman is already nearing menopause when receiving chemo, it may speed up the process, according to the MD Anderson Cancer Center at the University of Texas.
How does menopause impact treatment side effects?
Women who are older and more likely to have gone through menopause might have more difficulty when it comes to weathering certain breast cancer treatments, such as chemotherapy. However, overall health and other medical conditions also play an important role in how well someone tolerates treatment.
“There are some patients where we would not think twice about giving a standard dose in a regimen of chemotherapy,” says Dr. Goetz. “On the other hand, older patients who are diagnosed with triple-negative breast cancer may not be able to tolerate the same amount of chemotherapy, especially for patients who are in their late 60s, or early 70s.”
Menopause and cancer recurrence
For some premenopausal women with hormone receptor-positive breast cancer, reducing estrogen levels can help lower the risk of the disease coming back. So if a premenopausal patient is at particularly high risk for recurrence, a doctor may recommend ovarian suppression to reduce estrogen production. This can be done with medication or by surgically removing the ovaries.
“If we reduce hormones, we cut off the food for the cancer cells,” says Dr. Karuturi.
