Gynecologic Cancer Risk and Hormone Therapy
Gynecologic Cancer Risk and Hormone Therapy
A complete guide for women with no known risk, elevated genetic risk, or a personal cancer history.
When women come to me to talk about menopausal hormone therapy, one concern comes up more than any other: cancer.
It's a fair concern, and it deserves a real answer instead of a quick reassurance. But "does MHT cause cancer?" isn't one question — it's three, and the answer depends entirely on where you're starting from. So I've divided this into the three situations I see most often in my practice:
- Women with no elevated risk and no history of cancer
- Women with elevated risk but no history of cancer
- Women with a history of cancer
Find yourself below, and let's look at what the evidence actually says.
If you have no known elevated risk
This is the woman who is interested in MHT and has no personal history of cancer and no known elevated risk based on family history or other markers.
Uterine (endometrial) cancer
Systemic estrogen therapy used alone can lead to an increased risk of endometrial cancer. This is precisely why estrogen is not prescribed by itself to a woman who still has her uterus. When estrogen is combined with progesterone or a progestin, the overall risk of endometrial cancer is actually lower.
If a woman on MHT has persistent bleeding — meaning longer than six months — an ultrasound is typically recommended to evaluate the uterine lining.
Vaginal estrogen is thought to have minimal to no impact on a person's risk of endometrial cancer.
Ovarian cancer
There is a very small increased relative risk of ovarian cancer in women who have ever used MHT. Relative risk can sound alarming on its own, so here is what it looks like in absolute numbers:
Over five years of use in women aged 50 to 54, there was approximately one additional ovarian cancer case per 1,000 patients, and one additional ovarian cancer death per 1,700 patients.
Among women using estrogen alone, there were roughly two additional ovarian cancer cases per 10,000 women-years.
Long-term follow-up of the Women's Health Initiative study noted that combined estrogen and progesterone therapy did not increase the incidence of ovarian cancer or ovarian cancer mortality.
Cervical cancer
The data here is more limited. Follow-up from the Women's Health Initiative noted no difference in cervical cancer incidence in women taking hormone therapy. Larger systematic reviews have indicated a reduced risk of squamous cell carcinoma and a weak increased risk of adenocarcinoma.
Overall, MHT is considered safe for the generally healthy midlife patient and does not confer an increased risk of gynecologic cancer.
If you have an elevated genetic risk
A number of genetic mutations may confer an increased risk of gynecologic malignancy. Some of the most commonly known are the BRCA1 and BRCA2 mutations and Lynch syndrome.
BRCA1 and BRCA2
Women with BRCA mutations have significantly elevated risks of breast cancer, ovarian cancer, and uterine papillary serous cancer.
For a woman with a known BRCA mutation, a risk-reducing bilateral salpingo-oophorectomy — removal of the ovaries and fallopian tubes, often abbreviated BSO — can reduce the risk of ovarian cancer by 80%.
As we've discussed recently, a BSO can plunge a woman into immediate menopause. That is not a gentle transition, and it's a real reason to have the hormone therapy conversation rather than assume the option is closed.
For these women, hormone therapy is generally considered safe, as long as the patient does not have a personal history of breast cancer.
For women with a history of breast cancer, systemic MHT is not recommended. Non-hormonal therapies are useful for treating symptoms, and vaginal estrogen may be acceptable — but it should be approved by the patient's medical oncologist.
Lynch syndrome
Lynch syndrome is another common genetic mutation that increases a woman's risk of multiple cancers, most notably colorectal cancer, but also endometrial, ovarian, breast, and other GI tract cancers.
Women with Lynch syndrome who have had a hysterectomy and BSO can safely receive MHT using estrogen alone. Women with an intact uterus also need to use progesterone.
In general, women with genetic mutations that increase their cancer risk can safely use MHT after risk-reducing surgery. Estrogen-only systemic therapy is preferred, unless progesterone is indicated.
If you have a history of gynecologic cancer
This is the group most often told "absolutely not" without much discussion. The honest answer is that it depends a great deal on which cancer, what grade, and what stage.
Endometrial cancer
In women with low-grade endometrial cancer, use of estrogen therapy is considered reasonable, and it should especially be discussed with women who have had an early BSO.
For a woman with higher-grade or later-stage endometrial cancer, estrogen therapy is not recommended. Non-hormonal therapies are the mainstay of treatment for these patients.
Uterine sarcoma
Uterine sarcoma is a malignancy of the muscle of the uterus. Many of these cancers express hormone receptors, so systemic hormone therapy is generally not recommended.
Ovarian, fallopian tube, and peritoneal cancer
While there are some specific types of these cancers where MHT is not recommended, in general hormone therapy may improve survival and decrease recurrence in patients who have undergone a total hysterectomy and BSO.
Cervical cancer
Cervical cancer commonly occurs in women in the perimenopausal age range, and treatment can often result in premature menopause. Cervical cancer is generally not a hormone-dependent malignancy, and hormone therapy does not appear to impact cancer outcomes.
Once the cancer is adequately treated, it is recommended to use estrogen and progesterone therapy, or estrogen with bazedoxifene, for systemic treatment of menopausal symptoms.
A cancer history does not automatically close the door on hormone therapy. It does mean the decision needs to be made carefully, with your oncology team involved, and based on the specifics of your diagnosis rather than a blanket rule.
Where this leaves you
Numbers are much easier to sit with when someone walks you through them in the context of your own history. If you've been living with untreated menopausal symptoms because you assumed hormone therapy wasn't an option for you, that assumption is worth revisiting — out loud, with a physician who has the time to go through it properly.
With much love,
Dr. Riedel
This article is for general education and is not a substitute for individual medical advice. Decisions about hormone therapy should be made with your own physician, and where a cancer history is involved, in coordination with your oncology team.
