HERE'S ANOTHER WAY TO THINK OF IT....:

The excessive focus on mammography: Looking harder to find more may not be the best practice. (H. Gilbert Welch, November 3, 2008, LA Times)

But here's some good news about the bad news: The harm of over-diagnosis is not a fixed attribute of screening mammography. Instead, it is related to how hard we look for breast cancer. Some women harbor small, innocuous breast cancers that will never cause symptoms or death (just as some men harbor small, innocuous prostate cancers). The harder we look, the more likely we are to find these cancers.

To understand the problem, use Google Earth to count the number of lakes in Utah. When viewing the entire continent, you'll only see one -- Great Salt Lake. Now zoom in a bit. You'll find two more -- Utah Lake next to Provo and Bear Lake on the Idaho border -- but they're smaller. Now look even harder. Multiple lakes will suddenly appear high in the Uinta Mountains and the Wasatch Range. But they are smaller still.

The harder you look, the more lakes you find -- but they become smaller and less important.

"Look harder, find more" has been the prevailing paradigm in breast cancer screening from the outset. News reports focus on which approach finds more cancer. Conventional versus digital mammograms? Digital is better because it finds more cancer. Mammograms versus MRI? MRI is better because it finds more cancer. But the problem of over-diagnosis means that finding more cancer is not better -- it's the wrong way to measure progress. Real progress would be to find only the cancers that matter.

Screening proponents fear that women can't deal with the nuance. that mammography helps some and hurts others -- or any messages that might discourage women from having a mammogram every year. But leaving women in the dark exacerbates the problem of over-diagnosis.

How? Women who don't know about over-diagnosis don't question the "look harder, find more" paradigm -- and then all the forces line up to make the problem worse. Radiologists look harder at mammograms, pathologists look harder at biopsy specimens -- both only afraid of missing cancer, not over-diagnosis. Medical journals will continue to conclude (as will the news media that cover them) that the best test is always one that sees more, not less.

Women should be aware that looking harder may not be in their interest. And that doctors who recommend less-aggressive mammography (less frequently, waiting until you are age 50, or stopping it when you are older) or are less quick to biopsy may not be bad doctors but good ones. And women should demand (and participate in) research that looks less hard, finds less cancer -- but finds the cancers that matter.

Suppose we just pretended that every woman who has a pinky finger on her left hand had breast cancer and we removed the finger. The death rate of women "with breast cancer" would plummet dramatically.

Posted by Orrin Judd at November 3, 2008 8:11 AM