Combined screening with a CA-125 blood test and transvaginal ultrasound for early detection of ovarian cancer did not reduce the risk of dying from the disease and resulted in a large number of false positives and related biopsies and follow-up procedures, according to a study to be presented during the annual meeting of the American Society of Clinical Oncology June 3-7 in Chicago.
Results of the randomized, multicenter screening study of nearly 80,000 women in the general population indicate that while these tests are widely and appropriately used to evaluate symptoms and to gauge disease status and effectiveness of treatment in women already diagnosed with ovarian cancer, they are not useful in screening the general population.
“There hasn’t been a good method for the early detection of ovarian cancer, and our hypothesis was that CA-125 and transvaginal ultrasound, which are useful in measuring disease, would also identify ovarian cancer early at a stage in which it is more likely to be cured,” said the study's lead author Saundra Buys, MD, professor of medicine at the University of Utah and Huntsman Cancer Institute in Salt Lake City.
“The results were disappointing, but not necessarily surprising. The study shows that the available tests are not effective and may actually cause harm because of the high number of false positives. These results point to the continued need for more precise and effective screening tools for this disease.”
In the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial, 78,216 women ages 55 to 74 were assigned to either annual screening (39,105 women) or usual care (39,111 women) between 1993 and 2001. Women in the screening arm were offered annual CA-125 testing for six years and transvaginal ultrasound for four, and followed for up to 13 years. Those in the usual care arm were not offered the screening tests.
The results showed no statistically significant difference in ovarian cancer cases or mortality between the two arms. Ovarian cancer was diagnosed in 212 women in the screening group arm compared to 176 in the usual care arm; 118 women in the screening arm died from ovarian cancer, while 100 died from ovarian cancer in the usual care group.
Among women in the screening arm, there were 3,285 false positives compared to 212 true positives. Of women who had a false positive test, 1,080 underwent surgery for biopsy and 163 of them had serious complications.
The authors emphasized that the study results don’t apply to screening women with symptoms or abnormal findings on a physical exam. Physical exams based on symptoms and appropriate follow-up testing remain the best available approach for ovarian cancer detection, they explained.