Description of the Evidence
A CA-125 screening program of 22,000 postmenopausal women with subsequent transabdominal ultrasound for those with elevated CA-125 levels (reference value of 30 U/mL) detected 11 of 19 cases of ovarian cancer occurring in the cohort, for an apparent sensitivity of 58%. The specificity for this screening study was 99.9%. Three of the 11 cases detected through screening were stage I disease. In one prospective screening study, the specificity of CA-125 levels of 35 U/mL was 97.6%.
Evaluation of longitudinal measurements, incorporating the information into an algorithm termed "risk of ovarian cancer algorithm" or ROCA, is being evaluated in the UKCTOCS. The UKCTOCS is evaluating two-stage screening with ROCA as the primary screen and TVS as a secondary screen (based on results of the ROCA) for its impact on ovarian cancer mortality compared with TVS alone or no screening. Estimated sensitivity data for multimodality two-stage screening with ROCA followed by TVS has been published from the prevalent screen. Of the 50,078 women who underwent the prevalent screen in the multimodality screening arm, 409 were determined to have an intermediate or elevated risk of ovarian cancer based on the ROCA and were referred for TVS. Of the 409 women,167 women were referred for clinical evaluation, 97 underwent surgery, and 42 were diagnosed with either malignant ovarian or fallopian tube cancers. Among the women who had negative screens, five were diagnosed with ovarian or fallopian tube cancer within 1 year of screening. The estimated sensitivity was 89.4% (95% CI, 76.9–96.5%).
Combined CA-125 and TVU
The objective of the ovarian component of the PLCO trial was to evaluate the effect of screening on ovarian cancer mortality. The trial included 78,216 women aged 55 to 74 years who were randomly assigned to undergo either annual screening (n = 39,105) or usual care (n = 39,111) at ten screening centers across the United States between November 1993 and July 2001. The intervention group was offered annual screening with CA-125 for 6 years and TVU for 4 years. Participants and their health care practitioners received the screening test results and managed evaluation of abnormal results. The usual care group was not offered screening with CA-125 or TVU but received their usual medical care. Participants were followed for a maximum of 13 years (median, 12.4 years; range, 10.9–13.0 years) for cancer diagnoses and death until February 28, 2010. Mortality from ovarian cancer, including primary peritoneal and fallopian tube cancers, was the main outcome measure. Secondary outcomes included ovarian cancer incidence and complications associated with screening examinations and diagnostic procedures.