Endometrial Cancer

In the USA, endometrial cancer is the most common gynecologic malignancy and the fourth most common malignancy in women after breast, colorectal, and lung cancer. About 34,000 new cases of endometrial cancer were diagnosed in 1996. It affects mainly postmenopausal women, with incidence peaking between ages 50 and 60; < 5% of cases occur among women < 40 yr.

Etiology and Pathology

Endometrial cancer is more common in industrialized countries in which dietary fat intake is high. The most significant risk factor is obesity, which increases risk by 3 to 10 times. Endometrial cancer is more common in women with conditions that tend to result in unopposed estrogen (high circulating levels of estrogen with no or low levels of progesterone), such as unopposed estrogen replacement therapy, obesity, polycystic ovarian syndrome, nulliparity, late menopause, estrogen-producing tumors, anovulation, or oligo-ovulation. Women with a history of pelvic radiation therapy or with a personal or family history of breast or ovarian cancer are at increased risk. A small percentage of cases may be hereditary.
Endometrial hyperplasia usually precedes endometrial cancer and is classified by the degree of cytologic atypia. Its treatment consists of progestins or surgery, depending on the complexity of the lesion and the patient's desire to avoid hysterectomy.

Endometrial cancer may spread from the surface of the uterine cavity to the cervical canal; through the myometrium to the serosa and into the peritoneal cavity; via the lumen of the fallopian tube to the ovary, broad ligament, and peritoneal surfaces; via the bloodstream, leading to distant metastases; or via the lymphatics. The higher (more undifferentiated) the grade of the tumor, the greater likelihood of deep myometrial invasion, pelvic or para-aortic lymph node metastases, or extrauterine spread.

Adenocarcinoma accounts for > 80% of cases of endometrial cancer. Sarcomas account for about 5% of all uterine malignancies and include mixed mesodermal tumors, leiomyosarcomas, and endometrial stromal sarcomas. Sarcomas tend to be more aggressive, are more likely to produce local, regional, and distant metastases, and have a worse prognosis.

Symptoms, Signs, and Diagnosis

More than 90% of patients with endometrial cancer have abnormal uterine bleeding (eg, postmenopausal bleeding, premenopausal recurrent metrorrhagia). About 1/3 of women with postmenopausal bleeding have endometrial carcinoma. In postmenopausal women, a vaginal discharge may precede bleeding by several weeks or months.

If a Papanicolaou (Pap) smear shows endometrial cells in a postmenopausal woman or atypical endometrial cells in a woman of any age, further evaluation is indicated. However, a Pap smear does not accurately detect endometrial malignancies.

Tissue sampling from the endometrium, usually performed in the physician's office, is the definitive diagnostic procedure. This procedure is > 90% accurate, compared with a fractional dilation and curettage with hysteroscopy, performed in the operating room. The latter is used when outpatient sampling is not diagnostic. Transvaginal ultrasonography may also be useful.