Testing for Early-Stage Ovarian Cancer
by Margaret Snow, MD, and Sue Friedman
Women with a BRCA mutation or a mismatch repair gene mutation that causes hereditary nonpolyposis colorectal cancer (HNPCC) have a high lifetime risk of ovarian cancer. Without reliable early detection, ovarian cancer is usually diagnosed at stage III or IV and has a high mortality rate. If we could detect and treat ovarian cancer at an early stage, as we often do with breast cancer, the long-term survival rate for ovarian cancer would likely improve . But while current technology can identify precancerous changes in breast tissue, we have no reliable way to identify pre-cancer or early cancers in the ovaries or fallopian tubes.
Because the risk of ovarian and fallopian tube cancer is so high in genetically at-risk women, genetics experts recommend that high-risk women consider salpingo-oophorectomy (surgical removal of the ovaries and tubes) at age 35 or after childbearing is completed. Although not without risk or side effects, salpingooophorectomy is currently the most effective way to lower the risk of ovarian cancer. Some women are unexpectedly found to have ovarian or fallopian tube cancer at the time of risk-reducing surgery. The procedure can be performed as an outpatient laparoscopic procedure for some women; others may need full abdominal surgery and require a hospital stay.
In premenopausal women, oophorectomy causes immediate menopause. For some, this earlier-than-usual menopause is manageable, with or without hormone replacement therapy. Others experience varying degrees of menopausal symptoms, which are sometimes severe; some women cannot take or prefer not to take hormone replacement. Many women who are not yet close to menopause struggle with their decision regarding prophylactic oophorectomy. Highrisk women who wish to have children, or who are not ready for surgery, have no reliable choices for managing their risk for ovarian cancer in the absence of dependable early detection.
If ovarian cancer could be found at an earlier stage, the outcome would likely improve for many women. One promising method of detection involves identifying particular protein markers—which appear in differing amounts between women with ovarian cancer and those without—in a woman’s blood or urine. Researchers and commercial laboratories hope these biomarkers can be developed into a reliable test for ovarian cancer that will effectively diagnose the disease at its earliest and most curable stage.
One research group from Yale University published promising research: their study identified six biomarkers that may discriminate between women who have ovarian cancer and those who don’t. Yale licensed these biomarkers to LabCorp, a commercial laboratory that packaged them into a blood test named OvaSure. Recently, LabCorp announced that it will make OvaSure available as a screening test to women at high risk of ovarian cancer.
Gynecology and cancer experts have raised concerns about the test. In the Yale research study, not all of the research samples were from high-risk women. The test was abnormal in some early-stage (I or II) ovarian cancers; however, it was normal in other early-stage cancers. A number of the stage I cancers detected were ovarian cancer cell types that are not usually seen in hereditary or BRCArelated ovarian cancer.
The Yale study included a very small number (13 out of 156 cancers) of stage I ovarian cancers. The test was not performed for screening; it was studied in women at the time of surgery to see if it could differentiate between women with cancer and those without.
There is no information about how well the test would work for screening or whether it would be better or worse than the recommended screening of CA125 and transvaginal ultrasound in high-risk women. No one has yet studied how to properly evaluate women with an abnormal OvaSure test. Experts caution that because there is no reliable way to image ovaries, and because cancers that occur in high-risk women may be tiny, the only way to be certain whether a woman with an abnormal test does or does not have ovarian cancer is to remove her ovaries and fallopian tubes and have them carefully examined by a pathologist.
Based on the data from the Yale study, it appears that only a small number of women with an abnormal test result will actually have ovarian cancer; there will be many false positive results. Because OvaSure test results have not been independently validated, the cost of the test may not be covered by insurance. Based on the preliminary status of the research and the above concerns, the Society of Gynecologic Oncologists, the professional society of experts who treat ovarian cancer, issued the following statement on July 2:
“After reviewing OvaSure’s materials, it is our opinion that additional research is needed to validate the test’s effectiveness before offering it to women outside of the context of a research study conducted with appropriate informed consent under the auspices of an institutional review board.”
In the meantime, Dr. Mark Greene of the National Cancer Institute continues to encourage BRCA-positive women to participate in clinical trials of new ovarian cancer screening strategies. Our participation in well designed prospective studies is imperative if scientists are to progress toward the development of better screening tests as quickly as possible.
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