Women's Health Specialists of St. Louis
Obstetrics and Gynecology

Articles - Uterine Cancer

Uterine cancer is the most common gynecologic cancer in the United States. Fortunately, the majority of cases are diagnosed at an early stage when surgery alone is often curative. The most common form of uterine cancer arises from the inner lining of the uterus or endometrium. The development of this type of cancer is felt to be related to stimulation of the lining by estrogen. Other factors that increase the risk of developing endometrial uterine cancer include genetic predisposition, and obesity. The common theme for many women who develop uterine cancer is the presence of an underlying hormonal imbalance which results in a disproportionately high amount of estrogen over time. For example, women who are not experiencing regular menstrual cycles may be at increased risk. This is because irregular menstrual cycles are often a symptom of lack of ovulation. When ovulation does not occur, the normal shedding of the lining of the uterus does not occur. This allows for the lining to be exposed to estrogen over a longer period of time. Similarly, women who begin their menstrual cycles early in life or who undergo late menopause are at increased risk for development of a uterine cancer. This is because the uterus is stimulated by estrogen over a longer period of time. Women with Polycystic Ovary Syndrome (PCOS) are at increased risk because of the associated hormone imbalance. The insulin resistance associated with PCOS likely increases the risk as well. Insulin resistance and Type II diabetes are risk factors for uterine cancer because the insulin-like growth factors are thought to further increase the growth of the lining. Obesity is also commonly associated with these disorders. Obesity is a strong risk factor for uterine cancer because obese women actually have higher levels of circulating estrogen. They are also more likely to have irregular menstrual cycles, and chronic illness such as diabetes. Birth control pills actually lower the risk for uterine cancer because it restores the balance of both estrogen and progesterone. It is this balance that controls the growth and shedding of the lining. This is why women on hormone replacement therapy who have a uterus must take both estrogen and progesterone so that the lining is not over stimulated. Women who have undergone a hysterectomy may take estrogen-only replacement because uterine stimulation is no longer a concern.

Though the majority of uterine cancers are thought to be the result of prolonged exposure of the uterus to high levels of estrogen, without a doubt, genetic predisposition also places women at increased risk. For example, the BRCA1 gene is associated with hereditary breast cancer and may also increase the risk for both uterine and ovarian cancer. Lynch II Syndrome which is associated with hereditary colon cancer also increases the risk for uterine cancer.

Most uterine cancers however, will occur spontaneously in women without a hereditary disorder and the majority will occur in post-menopausal women. Classically, women with uterine cancer will complain of post-menopausal vaginal bleeding that is not associated with a change in hormone replacement therapy. All women who experience post-menopausal bleeding should receive further evaluation. Though pap smears are a screening tool for cervical cancer, sometimes cells from the uterine cavity will be present. When cells from the uterine cavity are present on a Pap smear further evaluation is warranted. Further evaluation may consist of an ultrasound, biopsy of the lining of the uterus, or other procedures. Women with a personal history of breast or colon cancer should discuss their risks of other glandular cancers with their physicians. Women of any age who experience unexplained irregular bleeding or menstrual cycles less than 21days or more than 35 days should be evaluated for a hormone imbalance. Treatment of the imbalance may prevent chronic illness including uterine cancer.