Uterine cancer, or endometrial cancer, starts when a faulty gene signals the cells in the uterus' lining to begin to grow and multiply abnormally. Researchers don’t know exactly what triggers this gene, but scientists have been able to establish that there are certain factors that affect endometrial cancer risk. The major factors that increase the risk of this type of cancer are hormone levels, lifestyle choices, an inherited genetic susceptibility and a personal medical history of cancer. Some of the factors that increase endometrial cancer risk, such as diet, are a matter of personal choice, but others, such as race or age, are not.
Endometrial cancer risk is most directly affected by the balance of hormones in a woman’s body, particularly an increase in circulating estrogen. A woman’s risk of this type of cancer increases the more years she menstruates. Beginning to menstruate before the age of 12 or arriving at menopause later than the norm can increase the risk because the more menstrual periods a woman has had, the longer her uterus has been exposed to estrogen. Endometrial cancer risk also can be increased by menopausal hormone replacement therapy. Women who have either never been pregnant or who are infertile have a higher risk of uterine cancer because pregnancy diminishes the amount of circulating estrogen in the body.
Being overweight is also a factor that increases endometrial cancer risk. Fat tissue can cause some hormones to change into types of estrogen, which increases the amount of circulating estrogen in the body. Endometrial cancer is seen twice as frequently in overweight women and three times more often in women who are obese. Not exercising and following a high-fat diet are also associated with a higher risk of uterine cancer.
A woman who has had either breast cancer or ovarian cancer also has a higher risk of developing endometrial cancer. Some of the same risk factors for these two kinds of cancer are known to increase the risk for endometrial cancer as well. The treatments for breast cancer and ovarian cancer might also increase the risk for endometrial cancer. Radiation used to treat these cancers can be a risk factor for endometrial cancer. The breast cancer drug tamoxifen is known to behave like an estrogen in the uterus, causing the lining to grow, which increases endometrial cancer risk. Endometrial cancer is known to occur more often in some families, so a family history of this or other types of cancers puts a woman at an increased risk of endometrial cancer.
