We fund research that explores how risk factors such as smoking, poor nutrition, and lack of physical activity can affect the development of cancer.
The value must be greater than or equal to $5
The value must be lesser than $1M
Your gift is 100% tax deductible.
ACS & ASCO are Stronger Together: Cancer.Net content is now available on cancer.org.
Español
PDFs by language
Our 24/7 cancer helpline provides information and answers for people dealing with cancer. We can connect you with trained cancer information specialists who will answer questions about a cancer diagnosis and provide guidance and a compassionate ear.
Chat live online
Select the Live Chat button at the bottom of the page
Our highly trained specialists are available 24/7 via phone and on weekdays can assist through online chat. We connect patients, caregivers, and family members with essential services and resources at every step of their cancer journey. Ask us how you can get involved and support the fight against cancer. Some of the topics we can assist with include:
For medical questions, we encourage you to review our information with your doctor.
For decades, women have used hormone therapy to ease symptoms of menopause, such as hot flashes and sweating. This is called menopausal hormone therapy, and you may see it abbreviated as HT or MHT. You may also hear it described as hormone replacement therapy (HRT), postmenopausal hormone therapy (PHT), or postmenopausal hormones (PMH).
In the past, many doctors and their patients believed that MHT didn’t just help with hot flashes and other symptoms – it had important health benefits. But well-conducted studies have led many doctors to conclude that the risks of MHT often outweigh the benefits.
This information covers only how MHT can affect a woman’s risk of getting certain cancers. It does not cover other possible risks of MHT such as heart disease or stroke.
You can use this information when you talk to your doctor about whether MHT is right for you.
Menopause is the time in a woman’s life when the ovaries stop working and she stops having menstrual periods for good. Menopause is sometimes called the change of life, or the change.
The ovaries stop releasing eggs and making the female hormones, estrogen and progesterone. In the months or years leading up to natural menopause, menstrual periods may become less frequent and irregular, and hormone levels may go up and down. This time is called perimenopause or the menopausal transition. Since periods can become less frequent during this time, it can be hard to know when they have actually stopped (and you have gone through menopause) until you look back at a later time.
Women who have their ovaries removed by surgery (oophorectomy) or whose ovaries stop working for other reasons go through menopause, too, but much more suddenly (without the menopausal transition).
Women who have had their uterus removed (hysterectomy) but still have their ovaries stop having periods, but they don’t really go through menopause until their ovaries stop working. This is often determined based on symptoms, but your doctor can tell for certain by testing your blood for levels of certain hormones. Hormones made by the pituitary gland called luteinizing hormone (LH) and follicle stimulating hormone (FSH) help regulate the ovaries before menopause. When levels of estrogen get lower during menopause, the levels of FSH and LH go up. High levels of FSH and LH, along with low levels of estrogen, can be used to diagnose menopause. Blood tests for these may be helpful in a woman who has had her uterus removed.
Some drugs can turn off the ovaries and cause menstrual periods to stop for a time. Although this is not the same as menopause, it can lead to many of the same symptoms.
Most of the symptoms of menopause are linked to lower estrogen levels. Some symptoms – hot flashes and night sweats, for instance – tend to fade away at some point, whether or not they are treated. Other problems that start after menopause, like dryness and thinning of vaginal tissues and bone thinning, tend to get worse over time.
Because many of the symptoms and problems of menopause are linked to low levels of estrogen, this hormone has often been used in the past to treat menopause.
The hormones most commonly used to treat symptoms of menopause are estrogen and progesterone. (Progesterone and drugs that act like it are called progestins). Often, these 2 hormones are used together, but some women are given estrogen alone. It’s important to know which hormones you are talking about when looking at the risks.
Common estrogen preparations used to treat menopausal symptoms include conjugated equine estrogens (CEE or Premarin®) and estradiol, but several forms or types of estrogen are available.
There are also many progestins available, but medroxyprogesterone acetate (MPA or Provera®), is often used with an estrogen to treat menopausal symptoms. Some preparations contain both an estrogen and a progestin.
Androgens (male hormones like testosterone) are also sometimes used to treat menopausal symptoms. This is not common, though, and because only a few studies have looked at this practice, it isn’t clear how safe it is in the long run.
Tibolone is a synthetic hormone drug that can act like estrogen, progesterone, and testosterone in different tissues of the body. Because this drug isn’t available in the US, it’s not discussed here.
Treating menopausal symptoms with estrogen and progestin together is known as estrogen-progestin therapy (EPT) or combined hormone therapy. Although estrogen alone improves the symptoms of menopause, it increases the risk of cancer of the uterus ( endometrial cancer). Adding a progestin to the estrogen lowers the risk of endometrial cancer back to normal. Because of this, EPT is given to women who still have a uterus (those who have not had a hysterectomy). EPT can be given 2 ways:
The word “bio-identical” is sometimes used by sellers to describe hormone preparations that contain estrogens and progesterone with the same chemical structure as those found naturally in people. Sometimes, how much of the hormones the woman takes are adjusted based on blood tests of hormone levels. Marketers often describe bio-identical hormones as “natural,” and buyers often think that they’re safer than other forms of estrogen and progestin used to control menopause symptoms. But so far, there are no long-term studies of bio-identical hormones, and no studies have found that women taking bio-identical hormones have less serious side effects than women taking other forms of these hormones. For this reason, bio-identical hormones should be assumed to have the same health risks as any other type of hormone therapy.
Some herbal remedies and supplements are also described as natural ways to treat the symptoms of menopause. For more on this, see “Herbs and supplements” in the section called “What does it all mean?”
Treating menopausal symptoms with estrogen alone is known as estrogen therapy (ET). ET improves the symptoms of menopause, but it increases the risk of cancer of the uterus (endometrial cancer). Because of this, ET is only safe for women who don’t have a uterus (such as those who have had a hysterectomy).
Hormones can be given so that they enter the bloodstream and circulate to reach all parts of the body. This is called systemic hormone therapy, and it’s often used to treat the symptoms of menopause. Systemic hormone therapy includes:
Systemic hormones can help with certain symptoms of menopause, such as hot flashes and night sweats, as well as problems linked to thinning of the lining of the vagina (such as dryness that can make sex painful). They can also help prevent and treat osteoporosis (severe bone thinning).
Hormones, most often estrogen, can also be placed in or near the place that needs treatment. This is called topical hormone therapy. If small doses are used, little of the hormone is absorbed into the bloodstream, so it has little if any effect on the rest of the body.
For women in menopause, very small doses of estrogen can be placed inside the vagina as topical therapy to help treat dry or thinned vaginal tissues. This type of estrogen comes in the form of vaginal creams, rings, and tablets. Even though tiny amounts of hormone may enter the blood, most of it stays in the vaginal tissues. Because so little of the hormone gets into the blood, topical treatment doesn’t help with problems like hot flashes, night sweats, or osteoporosis. Generally, topical estrogen is not needed in women taking systemic hormones.
(As noted earlier, there’s a type of vaginal ring that delivers high doses of hormones to the whole body, which would be considered systemic treatment. If you’re unsure about the type of ring you have, check with your doctor.).
Different types of studies can be used to look at cancer risk from menopausal hormone therapy (MHT).
Randomized controlled trials: In this kind of study, a group of patients get the drug being studied (like MHT), and another (control) group gets a placebo (like a sugar pill). Results from this kind of study are powerful because which group a patient is in is based on chance. This helps assure that the groups are similar in all ways, such as risk for cancer, except for the drug that’s being studied. This is the best way to see the effects of a drug. These types of studies can also be double-blinded, which means neither the people in the study nor their doctors know which group they are in. This lowers the chance that thoughts or opinions about treatment could affect the study results. Unfortunately, these kinds of studies are costly, which limits the number of people in the study, how long the study can continue, and the number of studies done.
Observational studies: These kinds of studies collect information about a large group of people but don’t give them a certain treatment, such as a drug. In observational studies of MHT, the women and their doctors decide what hormone drugs, if any, the women take and for how long. These kinds of studies can also gather information about other factors that can influence cancer risk. Some observational studies gather data about what happened over previous years. Others follow (observe) people for years to look at how different factors (like MHT) affect cancer risk. Observational studies can be less costly than randomized clinical trials, so they’re more common and often enroll many more patients.
A major drawback of observational studies is that the people getting the treatment being studied may have different cancer risk factors than the people who aren’t. Plus, the treatment (like which drugs are used for MHT and how long they’re taken) can differ between the people being studied. This makes it less clear that the differences seen are only due to the drug being studied (like MHT) and not other factors.
When observational studies and randomized controlled trials have different results, most experts give more weight to the results of the randomized controlled trial.
Several large studies have looked at possible links between systemic hormone therapy in menopausal women and different types of cancer.
The main randomized studies of MHT were part of the Women’s Health Initiative (WHI). The WHI included 2 randomized placebo-controlled clinical trials of MHT in healthy women:
The WHI also conducted some observational studies. However, when we mention a WHI study below, we’re referring to one of the randomized studies.
Many observational studies have looked at MHT and cancer risk. One example is the Million Women Study. It enrolled over a million women aged 50 to 64 in the UK, collected information about hormone use and other health and personal details, and followed the women for many years. Not all of the women in the Million Women Study took MHT. Some of the women taking MHT were on ET, some were on EPT, and some took another drug. Some of the women on ET still had their uterus.
Studies show that EPT does not increase the risk of endometrial cancer (cancer in the lining of the uterus). It is linked to a higher risk of abnormal vaginal bleeding. Because vaginal bleeding after menopause can be a symptom of endometrial cancer, this often leads to further testing.
Based on the WHI study, taking EPT is linked to a higher risk of breast cancer. The longer EPT is used, the higher the risk. The risk returns to that of a woman who never used EPT (the usual risk) within 3 years of stopping the hormones. Breast cancers in women taking EPT are more likely to be found when they are bigger and have spread beyond the breast.
To put the risk into numbers, if 10,000 women took EPT for a year, it would result in up to about 8 more cases of breast cancer per year than if they had not taken hormone therapy (HT).
Taking EPT is also linked to increased breast density (as seen on a mammogram). Increased breast density can make it harder to find breast cancer on a mammogram.
Risk factors for ovarian cancer are harder to study because it is a less common cancer. Even when something increases the risk of developing ovarian cancer, the risk of actually getting this cancer is still likely to be low.
The WHI did not find a real difference in ovarian cancer risk with EPT. Although there were more cases of ovarian cancer in the women on EPT, this may have been due to chance because of the small number of women who were affected with this cancer.
However, a recent analysis combined the results of more than 50 studies, including randomized controlled trials and observational studies. This analysis found that women who took estrogen and progestin (progesterone) after menopause did have an increased risk of getting ovarian cancer. The risk was highest for women taking hormones, and decreased over time after the hormones were stopped.
To put the risk into numbers, if 1,000 women who were 50 years old took hormones for menopause for 5 years, one extra ovarian cancer would be expected to develop.
In the WHI study of EPT, the results were mixed. Women who took EPT had a lower risk of getting colorectal cancer at all, but the cancers they got were more advanced (more likely to have spread to lymph nodes or distant sites) than the cancers in the women not taking hormones.
Some observational studies have found a lower risk of colorectal cancer in women taking EPT, but some did not. So far, though, observational studies have not linked EPT with a higher risk of colorectal cancer.
EPT is not linked to a higher risk of getting lung cancer, but it is linked to a higher risk of dying from lung cancer.
EPT is not linked to a higher risk of any type of skin cancer (including both melanoma and other types of skin cancer).
In women who still have a uterus, using systemic ET has been shown to increase the risk of endometrial cancer (cancer of the lining of the uterus). The risk remains higher than average even after ET is no longer used. Although most studies that showed an increased risk were of women taking estrogen as a pill, women using a patch or high-dose vaginal ring can also expect to have an increased risk of endometrial cancer.
Because of this increased cancer risk, women who have gone through menopause and who still have a uterus are given a progestin along with estrogen. Studies have shown that EPT does not increase the risk for endometrial cancer.
Long-term use of vaginal creams, rings, or tablets containing topical estrogen doses may also increase the levels of estrogen in the body. It’s not clear if this leads to health risks, but the amounts of hormone are much smaller than systemic therapies.
ET is not linked to a higher risk of breast cancer. In fact, certain groups of women taking ET, such as women who had no family history of breast cancer and those who had no history of benign breast disease, had a slightly lower risk of breast cancer.
The WHI study of ET did not report any results about ovarian cancer.
However, a recent analysis combined the results of more than 50 studies, including randomized controlled trials and observational studies. This analysis found that women who took estrogen after menopause did have an increased risk of getting ovarian cancer. The risk was highest for women currently taking estrogen, and decreased over time after estrogen was stopped.
To put the risk into numbers, if 1,000 women who were 50 years old took estrogen for menopause for 5 years, one extra ovarian cancer would be expected to develop.
Observational studies have shown that women who take ET have a higher risk for ovarian cancer compared with women who take no hormones after menopause. The overall risk remains low, but it does increase the longer a woman uses ET. The risk of ovarian cancer goes down after a woman stops taking the hormone.
In the WHI study, ET did not seem to have any effect on the risk of colorectal cancer.
Observational studies have found a lower risk of colorectal cancer in women who have used ET for many years.
ET does not seem to have any effect on the risk of lung cancer.
ET is not linked to a higher risk of any type of skin cancer (including both melanoma and other types of skin cancer).
The decision to use estrogen, alone (ET) or with a progestin therapy (EPT), after menopause should be made by each woman and her doctor after weighing the possible risks and benefits. Things to think about include:
Other factors to consider include how bad the woman’s menopausal symptoms are and the type and dose of the hormones the doctor recommends.
The American Cancer Society has no position or guidelines regarding menopausal hormone therapy.
If you and your doctor decide that MHT is the best way to treat symptoms or problems caused by menopause, keep in mind that it is medicine and like any other medicine it’s best to use it at the lowest dose needed for as short a time as possible. And just as you would if you were taking another type of medicine, you need to see your doctor regularly. Your doctor can see how well the treatment is working, monitor you for side effects, and let you know what other treatments are available for your symptoms.
All women should report any vaginal bleeding that happens after menopause to their doctors right away – it may be a symptom of endometrial cancer. A woman who takes EPT does not have a higher risk of endometrial cancer, but she can still get it.
Women using vaginal cream, rings, or tablets containing only estrogen should talk to their doctors about follow-up and the possible need for progestin treatment.
For women who have had a hysterectomy (surgery to remove the uterus), a progestin does not need to be a part of hormone therapy because there’s no risk of endometrial cancer. Adding a progestin does raise the risk of breast cancer, so ET is a better option for women without a uterus.
Women should follow the American Cancer Society guidelines for cancer early detection, especially those for breast cancer. These guidelines can be found in Breast Cancer Early Detection.
Many over-the-counter “natural” (herbal) products are promoted in stores and online as helpful with menopausal symptoms. These include vitamins and soy-based and herbal products (like black cohosh and red clover). There are also endless arrays of special blends of herbs and vitamins that claim to reduce the discomforts of menopause.
These products are considered dietary supplements (not drugs). They have not been evaluated by the Food and Drug Administration (FDA) to be sure that they work or even that they are safe. Some supplements have been tested in small clinical trials, but often the studies only looked at taking the substance for a short time (months), so it isn’t clear how safe it would be if taken for a long time. Another concern has been applying the results of a study of a particular version and dose of a supplement to others that weren’t tested.
Most of the plain herbs that are touted for menopausal symptoms carry a low risk of harm for most women, but some can interact with other drugs and/or cause unexpected problems. You should discuss herbs or supplements with your doctor before taking them.
Well-controlled scientific studies are needed to help find out if these products work and if they are any safer than the hormone therapy drugs now in use.
Beware of products with “secret formulas” or hormone-like ingredients that may cause harm. In the past, some “natural herbal supplements” made in other countries have been found to contain actual drugs, some of which have been banned from the United States because they are dangerous. It’s your right to know exactly what you’re taking and what side effects and drug interactions it may have.
You can learn more in Dietary Supplements: What Is Safe?
The American Cancer Society medical and editorial content team
Our team is made up of doctors and oncology certified nurses with deep knowledge of cancer care as well as editors and translators with extensive experience in medical writing.
Anderson GL, Judd HL, Kaunitz AM, et al. Effects of estrogen plus progestin on gynecologic cancers and associated diagnostic procedures: The Women’s Health Initiative randomized trial. JAMA. 2003;290:1739-1748.
Anderson GL, Clebowski RT, Aragaki AK, et al. Conjugated equine oestrogen and breast cancer incidence and mortality in postmenopausal women with hysterectomy: extended follow-up of the Women’s Health Initiative randomised placebo-controlled trial. Lancet Oncol. 2012 Mar 6 (Epub ahead of print).
Beral V, Million Women Study Collaborators. Breast cancer and hormone-replacement therapy in the Million Women Study. Lancet. 2003;362:419-427.
Beral V, Million Women Study Collaborators. Ovarian cancer and hormone-replacement therapy in the Million Women Study. Lancet. 2007;369:1703-1710.
Calle EE, Feigelson HS, Hildebrand JS, et al. Postmenopausal hormone use and breast cancer associations differ by hormone regimen and histologic subtype. Cancer. 2009;115(5):936-945.
Chlebowski RT, Anderson GL, Manson JE, et al. Lung Cancer Among Postmenopausal Women Treated With Estrogen Alone in the Women’s Health Initiative Randomized Trial. J Natl Cancer Inst. 2010;102(18):1413-1421.
Chlebowski RT, Hendrix SL, Langer RD, et al. Influence of estrogen plus progestin on breast cancer and mammography in healthy postmenopausal women. JAMA. 2003;289:3243-3253.
Chlebowski RT, Kuller LH, Prentice RL, et al. Breast cancer after use of estrogen plus progestin in postmenopausal women. N Engl J Med. 2009;360(6):573-587.
Chlebowski RT, Schwartz AG, Wakelee H, et al. Oestrogen plus progestin and lung cancer in postmenopausal women (Women’s Health Initiative trial): a post-hoc analysis of a randomised controlled trial. Lancet. 2009;374:1243-1251.
Chlebowski RT, Wactawski-Wende J, Ritenbaugh C, et al. Estrogen plus progestin and colorectal cancer in postmenopausal women. N Engl J Med. 2004;350:991-1004.
Colditz GA. Relationship between estrogen levels, use of hormone replacement therapy, and breast cancer. J Natl Cancer Inst. 1998;90:814-823.
Collaborative Group on Epidemiological Studies of Ovarian Cancer. Menopausal hormone use and ovarian cancer risk: individual participant meta-analysis of 52 epidemiological studies. Lancet. 2015 Feb 13 (E pub ahead of print).
Danforth KN, Tworoger SS, Hecht JL, et al. A prospective study of postmenopausal hormone use and ovarian cancer risk. BJC. 2007;96:151-156.
Ettinger B, Selby J, Citron JT, et al. Cyclic hormone replacement therapy using quarterly progestin. Obstet Gynecol. 1994;83(5 Pt 1):693-700.
Fletcher SW, Colditz, GA. Failure of estrogen plus progestin therapy for prevention. JAMA. 2002;288:366-367.
Gapstur SM, Morrow M, Sellers TA. Hormone replacement therapy and risk of breast cancer with a favorable histology: Results of the Iowa Women’s Health Study. JAMA. 1999;281:2091-2097.
Geller, SE, Studee L. Botanical and dietary supplements for menopausal symptoms: What works, what does not. J Women’s Health. 2005;14:634-649.
Gold, EB, Flatt SW, Pierce JP, et al. Dietary factors and vasomotor symptoms in breast cancer survivors: The WHEL study. Menopause. 2006;13:423-433.
Grodstein F, Newcomb PA, Stampfer MJ. Postmenopausal hormone therapy and the risk of colorectal cancer: a review and meta-analysis. Am J Med. 1999;106(5):574-582.
Heiss G, Wallace R, Anderson GL, et al, WHI Investigators. Health risks and benefits 3 years after stopping randomized treatment with estrogen and progestin. JAMA. 2008;299:1036-1045.
Hildebrand JS, Gapstur SM, Feigelson HS, et al. Postmenopausal hormone use and incident ovarian cancer: Associations differ by regimen. Internat. J Cancer. 2010;127(12):2928-2935.
Hildebrand JS, Jacobs EJ, Campbell PT, et al. Colorectal cancer incidence and postmenopausal hormone use by type, recency, and duration in cancer prevention study II. Cancer Epidemiol Biomarkers Prev. 2009;18(11):2835-41.
Hill DA, Hill SR. Counseling patients about hormone therapy and alternatives for menopausal symptoms. Am Fam Physician. 2010;82(7):801-807.
Lacey JV, Mink PJ, Lubin JH, et al. Menopausal hormone replacement therapy and ovarian cancer. JAMA. 2002;288:334-341.
Li CI, Malone KE, Porter PL, et al. Relationship between long durations and different regimens of hormone therapy and risk of breast cancer. JAMA. 2003;289:3254-3263.
Low Dog T. Menopause: a review of botanical dietary supplements. Am J Med. 2005;118:98-108.
Mørch LS, Løkkegaard E, Andreasen AH, Krüger-Kjaer S, Lidegaard O. Hormone therapy and ovarian cancer. JAMA. 2009 Jul 15;302(3):298-305.
National Cancer Institute Fact Sheet. Menopausal Hormone Replacement Therapy Use and Cancer: Questions and Answers. 12/5/2011. Accessed at www.cancer.gov/cancertopics/factsheet/Risk/menopausal-hormones on October 15, 2014.
Nelson HD, Humphrey LL, Nygren P, Teutsch SM, Allan JD. Postmenopausal hormone replacement therapy. JAMA. 2002;288:872-881.
Newcomb PA, Longnecker MP, Storer BE, et al. Long-term hormone replacement therapy and risk of breast cancer in postmenopausal women. Am J Epidemiol. 1996;143-527.
Noller, KL. Estrogen replacement therapy and risk of ovarian cancer. JAMA. 2002;288:368-369.
Ritenbaugh C, Stanford JL, Wu L, et al. Conjugated equine estrogens and colorectal cancer incidence and survival: the Women's Health Initiative randomized clinical trial. Cancer Epidemiol Biomarkers Prev. 2008 Oct;17(10):2609-18. Epub 2008 Sep 30.
Schairer C, Lubin J, Troisi R, et al. Menopausal estrogen and estrogen-progestin replacement therapy and breast cancer risk. JAMA. 2000;283:485-491.
Simon MS, Chlebowski RT, Wactawski-Wende J, et al. Estrogen plus progestin and colorectal cancer incidence and mortality. J Clin Oncol. 2012 Nov 10;30(32):3983-90. Epub 2012 Sep 24. Erratum in: J Clin Oncol. 2013 Jun 1;31(16):2063.
Tang JY, Spaunhurst KM, Chlebowski RT, et al. Menopausal hormone therapy and risks of melanoma and nonmelanoma skin cancers: women's health initiative randomized trials. J Natl Cancer Inst. 2011 Oct 5;103(19):1469-75. Epub 2011 Aug 30.
Trabert B, Wentzensen N, Yang HP, et al. Ovarian cancer and menopausal hormone therapy in the NIH-AARP diet and health study. Br J Cancer. 2012 Sep 25;107(7):1181-1187. Epub 2012 Aug 28.
Tsilidis KK, Allen NE, Key TJ, et al. Menopausal hormone therapy and risk of ovarian cancer in the European prospective investigation into cancer and nutrition. Cancer Causes Control. 2011 Aug;22(8):1075-84. Epub 2011 Jun 3.
Weiderpass E, Adami HO, Baron JA, et al. Risk of endometrial cancer following estrogen replacement with and without progestins. J Natl Cancer Inst. 1999;91:1131-1137.
Weiderpass E, Baron JA, Adami HO, et al. Low-potency estrogen and risk of endometrial cancer: a case-control study. Lancet. 1999;353:1824-1828.
Women’s Health Initiative Steering Committee. Effects of conjugated equine estrogen in postmenopausal women with hysterectomy: The Women’s Health Initiative randomized controlled trial. JAMA. 2004;291:1701-1712.
Writing Group for the Women’s Health Initiative Investigators. Risks and benefits of estrogen plus progestin in healthy postmenopausal women: Principal results from the Women’s Health Initiative randomized controlled trial. JAMA. 2002;288:321-333.
Last Revised: February 13, 2015
American Cancer Society medical information is copyrighted material. For reprint requests, please see our Content Usage Policy.
Sign up to stay up-to-date with news, valuable information, and ways to get involved with the American Cancer Society.