Key Points
                    - Avoiding risk factors and increasing protective factors may help prevent cancer.    - The following risk factors increase the risk of endometrial cancer:          - Endometrial hyperplasia     - Estrogen     - Tamoxifen     - Obesity, weight gain, metabolic syndrome, and diabetes     - Genetic factors        - The following protective factors decrease the risk of endometrial cancer:         - Pregnancy and breast-feeding     - Combination oral contraceptives     - Physical activity     - Cigarette smoking        - It is not known if the following factors affect the risk of endometrial cancer:         - Weight loss     - Fruits, vegetables, and vitamins        - Cancer prevention clinical trials are used to study ways to prevent cancer.    - New ways to prevent endometrial cancer are being studied in clinical trials.
                
                
                    Avoiding risk factors and increasing protective factors may help prevent cancer.
                    Avoiding cancer risk factors may help prevent certain cancers. Risk factors include smoking, being overweight, and not getting enough exercise. Increasing protective factors such as quitting smoking and exercising may also help prevent some cancers. Talk to your doctor or other health care professional about how you might lower your risk of cancer.
                
                
                    The following risk factors increase the risk of endometrial cancer:
                    Endometrial hyperplasia     Endometrial hyperplasia is an abnormal thickening of the endometrium (lining of the uterus). It is not cancer, but in some cases, it may lead to endometrial cancer.        Estrogen     Estrogen is a hormone made by the body. It helps the body develop and maintain female sex characteristics. Estrogen can affect the growth of some cancers, including endometrial cancer.     A woman's risk of developing endometrial cancer is increased by being exposed to estrogen in the following ways:            - Estrogen-only hormone replacement therapy: Estrogen may be given to replace the estrogen no longer produced by the ovaries in postmenopausal women or women whose ovaries have been removed. This is called hormone replacement therapy (HRT), or hormone therapy (HT). The use of HRT that contains only estrogen increases the risk of endometrial cancer and endometrial hyperplasia. For this reason, estrogen therapy alone is usually prescribed only for women who do not have a uterus. HRT that contains only estrogen also increases the risk of stroke and blood clots. When estrogen is combined with progestin (another hormone), it is called combination estrogen-progestin replacement therapy. For postmenopausal women, taking estrogen in combination with progestin does not increase the risk of endometrial cancer, but it does increase the risk of breast cancer. (See the Breast Cancer Prevention summary for more information.)     - Early menstruation: Beginning to have menstrual periods at an early age increases the number of years the body is exposed to estrogen and increases a woman's risk of endometrial cancer.     - Late menopause: Women who reach menopause at an older age are exposed to estrogen for a longer time and have an increased risk of endometrial cancer.     - Never being pregnant: Because estrogen levels are lower during pregnancy, women who have never been pregnant are exposed to estrogen for a longer time than women who have been pregnant. This increases the risk of endometrial cancer.               Tamoxifen     Tamoxifen is one of a group of drugs called selective estrogen receptor modulators, or SERMs. Tamoxifen acts like estrogen on some tissues in the body, such as the uterus, but blocks the effects of estrogen on other tissues, such as the breast. Tamoxifen is used to prevent breast cancer in women who are at high risk for the disease. However, using tamoxifen for more than 2 years increases the risk of endometrial cancer. This risk is greater in postmenopausal women.      Raloxifene is a SERM that is used to prevent bone weakness in postmenopausal women. However, it does not have estrogen-like effects on the uterus and has not been shown to increase the risk of endometrial cancer.        Obesity, weight gain, metabolic syndrome, and diabetes     Obesity, gaining weight as an adult, or having metabolic syndrome increases the risk of endometrial cancer. Obesity is related to other risk factors such as high estrogen levels, having extra fat around the waist, polycystic ovary syndrome, and lack of physical activity.    Having metabolic syndrome increases the risk of endometrial cancer. Metabolic syndrome is a condition that includes extra fat around the waist, high blood sugar, high blood pressure, and high levels of triglycerides (a type of fat) in the blood.        Genetic factors     Hereditary nonpolyposis colon cancer (HNPCC) syndrome (also known as Lynch Syndrome) is an inherited disorder caused by changes in certain genes. Women who have HNPCC syndrome have a much higher risk of developing endometrial cancer than women who do not have HNPCC syndrome.    Polycystic ovary syndrome (a disorder of the hormones made by the ovaries), and Cowden syndrome are inherited conditions that are linked to an increased risk of endometrial cancer.    Women with a family history of endometrial cancer in a first-degree relative (mother, sister, or daughter) are also at increased risk of endometrial cancer.
                
                
                    The following protective factors decrease the risk of endometrial cancer:
                    Pregnancy and breast-feeding    Estrogen levels are lower during pregnancy and when breast-feeding. The risk of endometrial cancer is lower in women who have had children. Breastfeeding for more than 18 months also decreases the risk of endometrial cancer.       Combination oral contraceptives    Taking contraceptives that combine estrogen and progestin (combination oral contraceptives) decreases the risk of endometrial cancer. The protective effect of combination oral contraceptives increases with the length of time they are used, and can last for many years after oral contraceptive use has been stopped.    While taking oral contraceptives, women have a higher risk of blood clots, stroke, and heart attack, especially women who smoke and are older than 35 years.       Physical activity    Physical activity at home (exercise) or on the job may lower the risk of endometrial cancer.        Cigarette smoking     Smoking at least 20 cigarettes a day may lower the risk of endometrial cancer. The risk of endometrial cancer is even lower in postmenopausal women who smoke.    However, there are many proven harms of smoking. Cigarette smokers live about 10 years less than nonsmokers. Cigarette smokers also have an increased risk of the following:            - Heart disease.     -  Head and neck cancers.     -  Lung cancer.     -  Bladder cancer.     -  Pancreatic cancer.
                
                
                    It is not known if the following factors affect the risk of endometrial cancer:
                    Weight loss    It is not known if losing weight decreases the risk of endometrial cancer.       Fruits, vegetables, and vitamins    A diet that includes, fruits, vegetables, phytoestrogen, soy, and vitamin D has not been found to affect the risk of endometrial cancer.     Taking multivitamins has little or no effect on the risk of common cancers, including endometrial cancer.
                
                
                    Cancer prevention clinical trials are used to study ways to prevent cancer.
                    Cancer prevention clinical trials are used to study ways to lower the risk of developing certain types of cancer. Some cancer prevention trials are conducted with healthy people who have not had cancer but who have an increased risk for cancer. Other prevention trials are conducted with people who have had cancer and are trying to prevent another cancer of the same type or to lower their chance of developing a new type of cancer. Other trials are done with healthy volunteers who are not known to have any risk factors for cancer.    The purpose of some cancer prevention clinical trials is to find out whether actions people take can prevent cancer. These may include eating fruits and vegetables, exercising, quitting smoking, or taking certain medicines, vitamins, minerals, or food supplements.
                
                
                    New ways to prevent endometrial cancer are being studied in clinical trials.
                    Clinical trials are taking place in many parts of the country. Information about clinical trials can be found in the Clinical Trials section of the NCI website. Check NCI's list of cancer clinical trials for endometrial cancer prevention trials that are now accepting patients.