Endometrial Cancer: The Estrogen-Progesterone Balance

While medical researchers have not yet established exactly what causes various types of cancers, they have identified risk factors—those variables that place people in categories that appear more susceptible to particular carcinomas.

Estrogen is an important hormone that is produced in the ovaries and is responsible for stimulating the thickening of the lining of the uterus (endometrium) in preparation for pregnancy or menstruation. It also maintains secondary sexual characteristics and is thought to be necessary for bone health and the prevention of osteoporosis.

The presence of estrogen in a woman's body is balanced by the presence of another hormone called progesterone. This balance keeps the endometrium healthy, but a shift in this balance appears to increase a woman's likelihood of contracting endometrial cancer.

Women can be exposed to excess estrogen in a number of ways. A long stretch of estrogen production occurs if a woman begins menstruating early—before age twelve—or reaches menopause after age fifty, or both. Recently, scientists have discovered that hormone replacement therapy (HRT) to relieve the symptoms of menopause also appears to increase the risk of endometrial cancer, particularly if the estrogen is not taken with progesterone.

Fat tissue has been identified as a culprit in estrogen production because it can change other hormones into estrogens. Therefore, obesity places a woman at higher risk of endometrial cancer.

Studies have determined that, depending on how overweight they are, obese women are two to five times more likely to get endometrial cancer than women of normal weight. Generally, obesity is defined as having a body mass index (BMI) above 30, although some studies have established a higher risk for women who are overweight, with a BMI as low as 25.

A study of 1118 women conducted in Ontario and reported in Cancer Control in the year 2000 reports a correlation between high incidence of the disease and the consumption of animal fat.

The Ontario study also found a "protective effect" of alcohol, meaning that the daily consumption of a small amount of alcohol seems to be related to a lower incidence. Another surprising finding among several research studies is the decreased likelihood among smokers, particularly those who are post-menopausal or heavy, current smokers.

Medical experts are certainly not suggesting that women court liver disease by consuming large amounts of alcohol, nor are they suggesting that women increase their chances of getting lung cancer by smoking. They do recommend, however, a diet rich in vegetables and low in animal fat, which can potentially decrease the risk.

In general, a woman's likelihood of contracting endometrial cancer may be a combination of a number of factors that include her age, family history, and exposure to radiation. To determine your risk, discuss your history with your physician or gynecologist.