Screening for ovarian cancer using a transvaginal ultrasound or CA-125 protein test may detect the disease but also can produce many false positives, reports a National Cancer Institute study published in the November American Journal of Obstetrics and Gynecology. The upshot: an increased likelihood of unnecessary surgery.
The study is part of the NCI's Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial, known as PLCO, and analyzed baseline findings for women enrolled between 1993 and 2001. The long-term goal of the PLCO trial is to determine if screening with TVU and CA-125 decreases ovarian cancer mortality in women ages 55 to 74.
You can read the study abstract for free online.
Of the 28,816 healthy women who participated in the screening, 1,338, or 4.7 percent, had an abnormal TVU, and 402, or 1.4 percent, had an abnormal CA-125 blood test. Thirty-four women had abnormal results from both tests.
Women with abnormal results from one or both tests were administered a variety of diagnostic procedures to discover if the cancer was indeed present. Of that group, 570 women underwent surgery. All told, 29 tumors -- 20 of which were invasive -- were detected among women with abnormal screening results. Thus, 541 women had surgery but did not have cancer.
"Ovarian cancer is a disease that is often fatal, and both patients and physicians are anxious to find ways to detect it at an earlier, more curable stage," said study co-author Saundra Buys, M.D., of the University of Utah, Salt Lake City, in an NCI news release. "However, the results from the initial year of screening show that TVU and CA-125 cannot currently be recommended for widespread use in the general population. Future results from the additional PLCO screenings and subsequent follow-up will be needed before a final assessment of this screening strategy can be made."
To help women recognize the warning signs and symptoms of ovarian cancer, the PLCO team has created an online fact sheet.
In related news, another new study posits that ovarian tumors classified as serous borderline or low malignant potential may not be harbingers of aggressive ovarian cancer but may, in fact, be part of a different class of tumors.
The study was conducted by researchers from the NCI, Dana-Farber Cancer Institute in Boston and M.D. Anderson Cancer Center in Houston using a gene expression technique that reveals which genes are turned off or on in a cell. The researchers detected differences between the gene expression profiles of LMP tumors and high-grade ovarian tumors, suggesting that serous low-grade ovarian tumors are more similar to LMP tumors than to serous high-grade ovarian tumors.
"Patients with serous low-grade or high-grade ovarian tumors currently receive the same treatment, which is surgery followed by chemotherapy. However, the finding that low-grade tumors are more similar to LMP tumors has significant therapeutic implications," said Michael Birrer, M.D., Ph.D., study leader and head of the Molecular Mechanism Section at NCI, in a Nov. 15 news release about the study. "Women with low-grade invasive tumors may benefit from therapies that are different from those given to patients with high-grade tumors. Furthermore, the biochemical pathways identified in this study may provide targets for more rational therapies for these different tumor types."
