NEW YORK (Reuters Health) - Annual screening with ultrasound and a blood test called CA 125 usually misses early cases of ovarian cancer, according to a report in the journal Obstetrics and Gynecology. In addition, ovarian cancer screening often leads to unnecessary biopsies and other surgical procedures.

The findings are consistent with guidelines by the U.S. Preventative Services Task Force, which recommend against such screening. Nonetheless, the authors conclude, more data are needed to determine if annual ultrasound and CA 125 screening reduces deaths from ovarian cancer.

Early-stage ovarian cancer often has only mild or no symptoms. Because results of early screening to detect this cancer in the early stage is not precise, it is usually diagnosed after it has progressed and become more deadly. Less than 20 percent of all ovarian cancers in the U.S. are diagnosed before they spread outside of the ovary.

The current study included 34,261 women who were invited to undergo four rounds of annual screening as part of the Prostate, Lung, Colorectal, and Ovarian cancer screening trial. The percentage of women who agreed to screening ranged from 83.1 percent in the first year to 77.6 percent in the fourth year.

The screening exam was considered positive if the ultrasound showed abnormalities on the ovaries or if blood levels of CA 125 were above a certain point, lead author Dr. Edward Partridge, from the University of Alabama at Birmingham School of Medicine, and colleagues note.

Of the 89 cancers diagnosed, 60 were detected with screening, the report indicates. Unfortunately, 72 percent of those detected on screening were already at an advanced stage.

As noted, screening often led to unnecessary operations. Nearly 20 unneeded procedures, mostly biopsies, were performed for every cancer that was detected through screening.

In an accompanying editorial, Dr. David G. Mutch, from Washington School of Medicine, St. Louis, suggests that "more research with the development of new and better technologies is needed if we are going to help identify patients with ovarian cancer at an earlier stage."

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