Endometrial Cancer
The female reproductive system consists of two ovaries, two fallopian tubes, a uterus and a vagina. The ovaries produce two main female hormones - estrogen and progesterone. The balance between these two hormones changes each month, making the endometrium thicken during the early part of the monthly cycle. If no pregnancy occurs, the endometrium is then shed during the last phase of the menstrual cycle.
When the balance of these two hormones shifts toward more estrogen - which stimulates growth of the endometrium - a woman's risk of developing endometrial cancer increases. Factors that increase levels of estrogen in the body include:
- Many years of menstruation. If you started menstruating at an early age - before age 12 - and continue to have periods into your 50s, you're at greater risk of endometrial cancer than is a woman who menstruated for fewer years. The more years you have had periods, the more exposure your endometrium has had to estrogen.
- Never having been pregnant. Pregnancy seems to protect against endometrial cancer, although experts aren't sure exactly why this might be. The body produces more estrogen during pregnancy, but it produces more progesterone, too. Increased progesterone production offsets the effects of the rise in estrogen levels. Women with excess exposure to estrogen that isn't counteracted by progesterone tend to be at increased risk of endometrial cancer.
- Irregular ovulation. Ovulation, the monthly release of an egg from an ovary in menstruating women, is regulated by estrogen. Irregular ovulation or failure to ovulate can increase your lifetime exposure to estrogen. Ovulation irregularities have many causes, including obesity and a condition known as polycystic ovary syndrome (PCOS). This is a condition in which hormonal imbalances prevent ovulation and menstruation. Treating obesity and PCOS can help restore your monthly ovulation and menstruation cycle, decreasing your risk of endometrial cancer.
- Obesity. Ovaries aren't the only source of estrogen. Fat tissue can change some hormones into estrogen. Being obese can increase levels of estrogen in your body, putting you at a higher risk of endometrial cancer and other cancers. A high-fat diet also can add to your risk by promoting obesity. Some scientists even think that fatty foods may directly affect estrogen metabolism, further increasing a woman's risk of endometrial cancer.
- Diabetes. This is a risk factor for endometrial cancer mainly because obesity and type 2 diabetes often go hand in hand. However, some data suggest that women who have diabetes, whether they're obese or not, are at greater risk of endometrial cancer.
- Estrogen-only replacement therapy (ERT). Estrogen stimulates growth of the endometrium. Replacing estrogen alone after menopause may increase your risk of endometrial cancer. Taking synthetic progestin, a form of the hormone progesterone, with estrogen - combination hormone replacement therapy - causes the lining of the uterus to shed and actually lowers your risk of endometrial cancer. However, this combination may cause other health risks.
- Ovarian tumors. Some tumors of the ovaries may themselves be a source of estrogen, increasing estrogen levels.
Other factors that can increase your risk of endometrial cancer include:
- Age. Most endometrial cancers develop over many years. Therefore, the older you are, the greater your risk. Ninety-five percent of endometrial cancer occurs in women older than 40.
- Personal history of breast cancer or ovarian cancer. Some of the same risk factors for breast cancer and ovarian cancer also increase your risk of endometrial cancer.
- Tamoxifen treatment. One in every 500 women whose breast cancer was treated with tamoxifen will develop endometrial cancer. Although tamoxifen acts mostly as an estrogen blocker, it does have some estrogen-like effects and can cause the uterine lining to grow. If you're being treated with this hormone, see your doctor for an annual pelvic examination and be sure to report any unusual vaginal bleeding.
- Race. White women are more likely to develop endometrial cancer, but black women are much more likely to die of the disease.
- Hereditary nonpolyposis colorectal cancer (HNPCC). This inherited disease is caused by an abnormality in a gene important for DNA repair. Women with HNPCC also have a significantly higher risk of endometrial cancer as well as colon and other cancers.
Having risk factors for endometrial cancer doesn't mean you'll get the disease. It means that you're at risk and should be alert to possible signs and symptoms of the disease. Conversely, some women who develop endometrial cancer appear to have no risk factors for the disease. |
