Abnormal bleeding occurs in 98% of cases of endometrial cancer. Endometrial cancer almost always causes vaginal bleeding. In women who are definitely postmenopausal, any vaginal bleeding is considered abnormal until proven otherwise. So if you have stopped having your periods and are in menopause, but you experience vaginal bleeding, you should see your doctor promptly.
Women who are taking postmenopausal hormone replacement therapy (HRT) may have vaginal bleeding, depending on the schedule and type of hormones prescribed. If a women is experiencing bleeding on HRT, she should discuss this with her doctor.
Women who are still menstruating may experience:
- bleeding between periods
- overly-frequent periods (less than 21 days apart)
- prolonged, heavy periods
Bleeding may be excessive or may appear as mere spotting or as a blood-tinged discharge. Some women have abnormal vaginal discharge that is not bloody.
Symptoms in advanced cancer may include pelvic pain, a mass in the pelvis, or weight loss.
Endometrial cancer is mostly a disease of postmenopausal women. Most cases of endometrial cancer in the U.S. happen in women between the ages of 50 and 70 years of age. Fewer than 5% of cases occur in women younger than 40.
Obesity and diabetes are two important risk factors Figure 02. Studies have shown that the risk of endometrial cancer increases two-to-tenfold in obese women, with the greatest risk for the most overweight women.
Although diabetic women tend to be overweight, diabetes also appears to be an independent risk factor. Women with diabetes who are not overweight also develop endometrial cancer in greater numbers, and heavy women with diabetes are at higher risk than women of the same weight who do not have diabetes.
Figure 02. Body mass index (BMI) calculator
Taking estrogen without the counteracting hormone, progesterone, increases the risk of endometrial cancer. Tamoxifen (Nolvadex), a drug used to treat breast cancer, that acts like estrogen in the uterus, also increases the risk. When estrogen replacement therapy was first offered to women to help alleviate symptoms of menopause and enhance other aspects of health, rates of endometrial cancer increased significantly nationwide. Doctors now realize that progesterone, the female hormone that counteracts the effects of estrogen, must also be given as part of hormone replacement therapy for women who have not had a hysterectomy.
Tamoxifen is classified as an “anti-estrogen” drug, and is used to treat women with breast cancer as well as endometrial cancer in some cases. It does, however, act as a weak estrogen in the endometrium, and carries a 1 in 500 risk of causing endometrial cancer, which is about twice the rate of cancer in women who do not take tamoxifen. Because most of the endometrial cancers that develop as a result of tamoxifen are type I cancers and are stage I (see below), they have an excellent prognosis. Indeed, there is no increase in mortality from endometrial cancer that arises in these women.
Thus, for women who have had breast cancer, the benefits of taking tamoxifen to prevent a recurrence clearly outweigh the relatively lower risk of developing endometrial cancer. Healthy women who have a strong family history of breast cancer also may consider taking tamoxifen, but must more carefully assess the potential risks and benefits.
Women who take tamoxifen must be informed about the symptoms of endometrial cancer, and seek help if abnormal bleeding develops.
All women are naturally exposed to estrogen throughout their lives. However, some have relatively higher levels and are more at risk. Women who do not ovulate regularly (release an egg at midcycle) are more likely to develop a precancerous condition of the endometrium called endometrial hyperplasia. This condition results from abnormal regulation of the hormones associated with the menstrual cycle, and an excess of circulating estrogen for longer intervals during a woman's menstrual cycle. Women at risk for endometrial hyperplasia include those with polycystic ovarian syndrome, for example.
In addition, women who have more periods during their lives—those who start menstruation at an early age, go through late menopause, or have no children—are more likely to develop endometrial cancer.
Women who do not ovulate because ovulation is suppressed by birth control pills actually have a lower risk of endometrial cancer. Therefore, it is not the lack of ovulation that is the problem; it is the lack of proper regulation of ovulation, which also produces abnormal hormonal levels of estrogen and progesterone during the menstrual cycle.
Women who have had breast cancer, ovarian cancer, or certain colon cancers are at higher risk. Another inherited condition that is associated with a high rate of inherited colon and uterine cancer, called hereditary nonpolyposis colon cancer (Lynch II syndrome), is also associated with a high risk of endometrial cancer.
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