Cancer of the Uterus
Cancer of the uterus begins in the lining of the uterus (endometrium) and is more precisely termed endometrial cancer (carcinoma). It is the most common gynecologic cancer and the fourth most common cancer among women. This cancer usually develops after menopause, most often in women aged 50 to 60.
Risk factors for endometrial cancer include the following:
- early menarche (the start of menstrual periods), menopause after age 52, or both
- menstrual problems (such as excessive bleeding, spotting between menstrual periods, or long intervals without periods)
- never having had children
- tumors that produce estrogen
- high doses of drugs that contain estrogen, such as estrogen therapy without a progestin (synthetic drugs similar to the hormone progesterone), taken after menopause
- use of tamoxifen
- obesity
- high blood pressure
- diabetes
- family history of cancer of the breast, ovaries, large intestine (colon), or lining of the uterus.
Many of these conditions increase the risk of endometrial cancer because they result in a high level of estrogen but not progesterone. Estrogen promotes the growth of tissue and rapid cell division in the lining of the uterus (endometrium). Progesterone helps balance the effects of estrogen. Levels of estrogen are high during part of the menstrual cycle. Thus, having more menstrual periods during a lifetime may increase the risk of endometrial cancer. Tamoxifen, a drug used to treat breast cancer, blocks the effects of estrogen in the breast, but it has the same effects as estrogen in the uterus. Thus, this drug may increase the risk of endometrial cancer. Taking oral contraceptives that contain estrogen and a progestin appears to reduce the risk of endometrial cancer.
More than 80% of endometrial cancers are adenocarcinomas, which develop from gland cells. About 5% are sarcomas, which develop from connective tissue and tend to be more aggressive.
Symptoms and Diagnosis
Abnormal bleeding from the vagina is the most common early symptom. Abnormal bleeding includes bleeding after menopause or between menstrual periods and periods that are irregular, heavy, or longer than normal. One of three women with vaginal bleeding after menopause has endometrial cancer. Women who have vaginal bleeding after menopause should see a doctor promptly. A watery, blood-tinged discharge may also occur. Postmenopausal women may have a vaginal discharge for several weeks or months, followed by vaginal bleeding.
If doctors suspect endometrial cancer or if Pap test results are abnormal, doctors perform an endometrial biopsy in their office. This test accurately detects endometrial cancer more than 90% of the time. If the diagnosis is still uncertain, doctors perform dilation and curettage (D and C (see Section 22, Chapter 242)), in which tissue is scraped from the uterine lining. At the same time, doctors may view the interior of the uterus using a thin, flexible viewing tube inserted through the vagina and cervix into the uterus in a procedure called hysteroscopy.
If endometrial cancer is diagnosed, some or all of the following procedures may be performed to determine whether the cancer has spread beyond the uterus: blood tests, liver function tests, a chest x-ray, and computed tomography (CT) or magnetic resonance imaging (MRI). Other procedures are sometimes required. Staging is based on information obtained from these procedures and during surgery to remove the cancer.
Prognosis and Treatment
If endometrial cancer is detected early, nearly 90% of women who have it survive at least 5 years, and most are cured. The prognosis is better for women whose cancer has not spread beyond the uterus. If the cancer grows relatively slowly, the prognosis is also better. Fewer than one third of women who have this cancer die of it.
Hysterectomy, the surgical removal of the uterus, is the mainstay of treatment for women who have endometrial cancer. If the cancer has not spread beyond the uterus, removal of the uterus plus removal of the fallopian tubes and ovaries (salpingo-oophorectomy) almost always cures the cancer. Nearby lymph nodes are usually removed at the same time. These tissues are examined by a pathologist to determine whether the cancer has spread and, if so, how far it has spread. With this information, doctors can determine whether additional treatment (chemotherapy, radiation therapy, or a progestin) is needed after surgery.
Chemotherapy may be given after surgery, even when the cancer does not appear to have spread, in case some undetected cancer cells remain. More than half of women with cancer limited to the uterus do not need radiation therapy. However, if the cancer has spread, radiation therapy is usually needed after surgery.
A progestin is often effective. (Progestins are synthetic drugs similar to the hormone progesterone, which blocks the effects of estrogen on the uterus.) If the cancer has spread beyond the uterus, higher doses may be needed. In 15 to 30% of women who have cancer that has spread, a progestin reduces the cancer's size and controls its spread for 2 to 3 years or longer. A progestin may be continued as long as it seems to be working well. Side effects may include mood changes and weight gain due to water retention.
If the cancer has spread, is not responding to a progestin, or recurs, chemotherapy drugs (such as cisplatin, cyclophosphamide, doxorubicin, and paclitaxel) may be used instead of or sometimes with radiation therapy. These drugs are much more toxic than progestins and cause many side effects. However, they reduce the cancer's size and control its spread in more than half of women treated.
 See the sidebar Understanding Hysterectomy.
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