Health Letter, June 2018
By Michael Carome, M.D.
Ovarian cancer is the fifth-leading cause of cancer death, as well as the leading cause of death from gynecologic cancers, among women in the U.S. Approximately 14,000 U.S. women die each year from the disease. Most of these deaths occur in women 45 years and older.
Early-stage ovarian cancer typically does not cause any symptoms. When symptoms — which can include abdominal pain or pressure, bloating, constipation, urinary symptoms, back pain or fatigue — do occur, the disease usually has reached an advanced stage, making it more difficult to treat.
Treatment for ovarian cancer usually includes surgery and chemotherapy. For women who have the earliest stage of ovarian cancer, in which the tumor is limited to the ovary, the five-year survival rate is more than 90 percent. In contrast, for women with the most advanced stage of the disease, in which the cancer has spread to distant parts of the body, the five-year survival rate is about 30 percent.
Because most ovarian cancer cases are discovered at a late stage when the mortality rate is high, efforts have been made to develop a screening test to detect ovarian cancer at an early stage in women without symptoms of the disease. Two tests that have been used to screen women for ovarian cancer are transvaginal ultrasound (a procedure in which an ultrasound probe is inserted into the vagina to examine the uterus, fallopian tubes, ovaries, cervix and vagina) and a blood test for CA-125, a substance that often is elevated in the blood of patients with ovarian cancer and certain other cancers.
The U.S. Preventive Services Task Force (USPSTF), a volunteer panel of national experts in disease prevention and evidence-based medicine working independently of the drug and medical device industries, examined the scientific evidence for ovarian cancer screening using transvaginal ultrasound or the CA-125 blood test and issued a final statement recommending against such screening in women who are considered to be at average risk of the disease.
The USPSTF published its statement and the evidence that supported its recommendation in the Feb. 13 issue of the Journal of the American Medical Association.,
More harm than benefit
The USPSTF’s evidence review relied on four randomized clinical trials that evaluated the benefits and harms of ovarian cancer screening programs in women who had no symptoms and were considered to have an average risk of the disease. The four trials together enrolled nearly 300,000 women who were randomly assigned to ovarian cancer screening (with transvaginal ultrasounds, CA-125 blood tests or both) or to no screening or usual care.
The main outcomes of interest to the USPSTF from these trials were ovarian cancer mortality, false-positive screening results and surgery (screening test was positive, resulting in surgical treatment, but the subject did not have ovarian cancer), surgical complications and the psychological effects of screening.
The USPSTF’s review found adequate evidence that screening for ovarian cancer did not reduce ovarian cancer mortality in average-risk women.
However, ovarian cancer screening did result in harm: Screening led to surgery for suspected ovarian cancer in 1 to 3 percent of women without cancer, depending on which screening tests were used. Moreover, major surgery-related complications occurred in 3 to 15 percent of these women. The trials also revealed evidence of psychological harm associated with the screening, particularly in women who needed to undergo repeat follow-up scans and tests.
Given the results of its evidence review, the USPSTF concluded with at least moderate certainty that the harms of screening for ovarian cancer outweigh the benefits and recommended against such screening in women without symptoms.
Importantly, the USPSTF recommendation does not apply to women who have possible symptoms of ovarian cancer or who are at high risk of ovarian cancer, including:
- Women who have certain hereditary cancer syndromes, such as those with BRCA1 or BRCA2 genetic mutations associated with hereditary breast and ovarian cancer syndrome, and
- Women with a family history of ovarian or breast cancer.
The USPSTF’s recommendation against screening for ovarian cancer aligns with the recommendations of other major medical and public health organizations, including the American College of Obstetricians and Gynecologists, the American Cancer Society, the American College of Radiology and the American Academy of Family Physicians.
The USPSTF concluded that further research is needed to identify effective approaches for reducing ovarian cancer cases and deaths.