Cancer group says screenings are not a panacea

The American Cancer Society, which has long been a staunch defender of most cancer screening, is now saying that the benefits of detecting many cancers, especially breast and prostate, have been overstated.

It is quietly working on a message, to put on its Web site early next year, to emphasize that screening for breast and prostate cancer and certain other cancers can come with a real risk of overtreating many small cancers while missing cancers that are deadly.

"We don't want people to panic," said Dr. Otis Brawley, chief medical officer of the cancer society. "But I'm admitting that American medicine has overpromised when it comes to screening. The advantages to screening have been exaggerated."

Prostate cancer screening has long been problematic. The cancer society, which with more than 2 million volunteers is one of the nation's oldest and largest voluntary health agencies, does not advocate testing for all men. And many researchers point out that the PSA screening test for prostate cancer has not been shown to prevent cancer deaths.

There has been much less public debate about mammograms. Studies from the 1960s to the 1980s found that they reduced the death rate from breast cancer by up to 20 percent.

The cancer society's decision to reconsider its message about the risks as well as potential benefits of screening was spurred in part by an analysis published today in The Journal of the American Medical Association, Brawley said.

In it, researchers report a 40 percent increase in breast cancer diagnoses and a near doubling of early stage cancers, but just a 10 percent decline in cancers that have spread beyond the breast to the lymph nodes or elsewhere in the body. With prostate cancer, the situation is similar, the researchers report.

If breast and prostate cancer screening really fulfilled their promise, the researchers note, cancers that once were found late, when they were often incurable, would now be found early, when they could be cured. A large increase in early cancers would be balanced by a commensurate decline in late-stage cancers. That is what happened with screening for colon and cervical cancers. But not with breast and prostate cancer.

Still, the researchers and others say, they do not think all screening will — or should — go away. Instead, they say that when people make a decision about being screened, they should understand what is known about the risks and benefits.