- Risk Factors
- Lowering Risk
Cancer prevention is action taken to lower the chance of getting cancer. By preventing cancer, the number of new cases of cancer in a group or population is lowered. Hopefully, this will lower the number of deaths caused by cancer.
To prevent new cancers from starting, scientists look at risk factors and protective factors. Anything that increases your chance of developing cancer is called a cancer risk factor; anything that decreases your chance of developing cancer is called a cancer protective factor.
Some risk factors for cancer can be avoided, but many cannot. For example, both smoking and inheriting certain genes are risk factors for some types of cancer, but only smoking can be avoided. Regular exercise and a healthy diet may be protective factors for some types of cancer. Avoiding risk factors and increasing protective factors may lower your risk but it does not mean that you will not get cancer.
Different ways to prevent cancer are being studied, including:
- Changing lifestyle or eating habits.
- Avoiding things known to cause cancer.
- Taking medicines to treat a precancerous condition or to keep cancer from starting.
Endometrial cancer is a disease in which malignant (cancer) cells form in the tissues of the endometrium.
The endometrium is the lining of the uterus. The uterus is part of the female reproductive system. It is a hollow, pear-shaped, muscular organ in the pelvis, where a fetus grows.
Cancer of the endometrium is different from cancer of the muscle of the uterus, which is called sarcoma of the uterus. See the PDQ summary on Uterine Sarcoma Treatment for more information.
Endometrial cancer is the most common invasive cancer of the female reproductive system.
Endometrial cancer usually occurs in women after menopause, and affects more white women than black women. Black women diagnosed with endometrial cancer are more likely to have more advanced disease at diagnosis, and are more likely to die from endometrial cancer than white women.
Avoiding risk factors and increasing protective factors may help prevent endometrial cancer.
Having a risk factor does not mean that you will get cancer; not having risk factors doesn't mean that you will not get cancer. Most people with a certain risk factor for cancer do not usually get the disease. Doctors cannot always explain why one person gets cancer and another does not. Talk to your doctor or other health care professional about ways to reduce your risk of cancer.
The following risk factors may increase the risk of endometrial cancer:
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 hormone replacement therapy that contains only estrogen increases the risk of endometrial cancer. For this reason, estrogen therapy alone is usually prescribed only for women who do not have a uterus. 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.
- 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 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. When tamoxifen is used to prevent breast cancer in women who are at high risk for the disease, it 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. It does not have estrogen-like effects on the uterus and has not been shown to increase the risk of endometrial cancer. Other SERMs are being studied in clinical trials.
Hereditary nonpolyposis colon cancer (HNPCC) 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
Women who have polycystic ovary syndrome (a disorder of the hormones made by the ovaries) have an increased risk of endometrial cancer.
Obesity increases the risk of endometrial cancer. This may be because obesity is related to other risk factors such as estrogen levels, polycystic ovary syndrome, lack of physical activity, and a diet that is high in saturated fats.
It is not known if losing weight decreases the risk of endometrial cancer.
The following protective factors may decrease 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.
Physical activity may lower the risk of endometrial cancer.
Pregnancy and breast-feeding
Estrogen levels are lower during pregnancy and when breast-feeding. Being pregnant and/or breast-feeding may lower the risk of endometrial cancer.
A diet low in saturated fats and high in fruits and vegetables may lower the risk of endometrial cancer. The risk may also be lowered when soy-based foods are a regular part of the diet.
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 Web site. Check NCI's PDQ Cancer Clinical Trials Registry for endometrial cancer prevention trials that are now accepting patients.