New Tests in Fight Against Ovarian Cancer
Ovarian cancer has recently been thrust into the limelight. First came comedian Gilda Radner’s illness and death in 1989. Then “thirtysomething†character Nancy Weston endured a two-year prime-time battle with the disease. The attendant publicity has increased our awareness of ovarian cancer--and spawned confusion over just how women should respond to the threat.
Although the American Cancer Society predicts that 20,700 new cases will be diagnosed this year, ovarian cancer is relatively rare, affecting about one in 70 women, contrasted with one in nine who eventually develop breast cancer. But ovarian cancer is often fatal, causing more deaths than uterine cancer, the most common gynecological tumor. Only about one in three women with the disease survive for five years or more.
The problem is less with treatment--85% to 90% of cancers confined to the ovary can now be cured--than with the great difficulty in detecting tumors before they spread. Symptoms usually don’t occur until the disease is far advanced. And unlike cervical cancer with its Pap test, ovarian cancer has so far resisted efforts to develop tests suitable for mass screening.
Several factors influence a woman’s susceptibility. While the cases of Radner and Weston suggest that younger women are especially vulnerable, risk actually rises with age, with most cases occurring after menopause. Risk doubles for older women who have never had children or who have previously had breast or endometrial cancer. But the most important risk factor is a family history of the disease.
“Knowing your family history is vital,†says Dr. M. Steven Piver, chief of gynecologic oncology at the Roswell Park Cancer Institute in Buffalo, N.Y., who pinpointed the strong genetic link in the late 1970s. Radner, he says, “was sitting on a time bomb†since--unknown to her--a grandmother, an aunt and a cousin all had ovarian cancer and her mother had breast cancer.
Piver has found that women with two or more close relatives (mother, sister, daughter) with ovarian cancer have a 50-50 chance of developing it themselves. Piver and other experts now urge high-risk women, if they’re older than 40 and are finished with childbearing, to consider having their ovaries removed as a preventative measure. At the very least, high-risk women should get gynecological checkups twice a year.
Though family history provides a valuable tip-off to risk, it probably figures in no more than 5% of ovarian cancer cases. What about the great majority of women not at high risk: Just how aggressively should they be screened for the disease? Experts disagree on the answer.
The primary test for detecting ovarian cancer is the standard pelvic exam, in which the doctor feels a woman’s ovaries to detect enlargement. Unfortunately, by the time a change in size is noticeable, the cancer has usually spread throughout the abdominal cavity and even to other parts of the body.
Two new tests have attracted considerable attention: transvaginal ultrasound (a non-invasive technique for “imaging†the ovary) and CA 125 (a blood test that detects a protein shed by ovarian tumors).
In recent appearances on TV programs, Piver has urged high-risk women to ask for both tests to augment their pelvic exams. Other experts go even further, recommending that both tests be used for all women. The upshot, say gynecologists, is that many worried but low-risk women of all ages are now asking for the tests--which may do them more harm than good.
The CA 125 blood test (CA stands for cancer antigen) has proved useful for monitoring the success of ovarian-cancer treatment, indicating whether a tumor has shrunk or if the cancer has recurred. But the test works less well at detection and misses about half of all early tumors. In addition, false diagnoses are frequent because four other cancers (breast, colon, pancreatic and liver) as well as unrelated gynecologic problems including endometriosis and fibroids (benign tumors of the uterus) can also elevate CA 125 levels.
Transvaginal ultrasound uses a recently developed probe that can reach within millimeters of ovaries, producing detailed images on a computer screen. The image can reveal an ovarian mass--helpful in confirming an abnormal pelvic exam--but it can’t distinguish between tumors and benign ovarian cysts, which are especially common in younger women.
