2011 ASCO: Screening With CA-125 & Transvaginal Ultrasound Does Not Reduce Ovarian Cancer Death Rate, Results in High Number of False Positives

Findings from a large, long-term study – the Prostate, Lung, Colorectal and Ovarian (PLCO) Screening Trial – showed that using 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 follow-up procedures.

ASCO Releases Studies From Upcoming Annual Meeting – Important Advances in Targeted Therapies, Screening, and Personalized Medicine

The American Society of Clinical Oncology (ASCO) today highlighted several studies in a press briefing from among more than 4,000 abstracts publicly posted online at http://www.asco.org in advance of ASCO’s 47th Annual Meeting. An additional 17 plenary, late-breaking and other major studies will be released in on-site press conferences at the Annual Meeting.

The meeting, which is expected to draw approximately 30,000 cancer specialists, will be held June 3-7, 2011, at McCormick Place in Chicago, Ill. The theme of this year’s meeting is “Patients. Pathways. Progress.”

“This year marks the 40th anniversary of the signing of the National Cancer Act, a law that led to major new investments in cancer research. Every day in our offices, and every year at the ASCO meeting, we see the results of those investments. People with cancer are living longer, with a better quality of life, than ever before,” said George W. Sledge Jr., M.D., President of ASCO, Ballve-Lantero Professor of Oncology and professor of pathology and laboratory medicine at the Indiana University School of Medicine.

“With our growing understanding of the nature of cancer development and behavior, cancer is becoming a chronic disease that a growing number of patients can live with for many years,” said Dr. Sledge. “The studies released today are the latest examples of progress against the disease, from new personalized treatments, to new approaches to screening and prevention.”

The study results from a large clinical trial involving ovarian cancer screening were highlighted in today’s press briefing as summarized below.

Screening with CA-125 and Transvaginal Ultrasound Does Not Reduce Ovarian Cancer Death Rate, Results in High Number of False Positives

A randomized, multicenter screening study of nearly 80,000 women in the general population showed that using 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. The results 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.

Saundra S. Buys, M.D., Medical Director, Huntsman Cancer Institute’s High Risk Breast Cancer Clinic; Professor, Depart. of Internal Medicine, Univ. of Utah School of Medicine

“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 lead author Saundra Buys, M.D., 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 a high number of false positives – 3,285 false positives, compared to just 212 true positives. Of women who had a false positive test, 1,080 underwent surgery for biopsy – the procedure generally required to evaluate positive test results; 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 physical examination. [emphasis added] Physical examination based on symptoms and appropriate follow-up testing remains the best available approach for ovarian cancer detection.

[Note: This summary contains updated data and a correction from the original abstract. Correction:  Of the 3,285 women who received a false positive exam, 1,080 underwent surgery. Of those surgical patients, 163 encountered at least one serious complication.]

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