Each time I open my e-mail, I scan a long list of subject lines to find the messages that have something important to tell me. Occasionally, I’ll miss one and have to go back later to find it. Sometimes I make a different kind of mistake, opening a missive of no consequence. The point is that, even in a simple system like my in-box (OK, not that simple — the current count shows 19,004 unopened messages), detecting the signal from the noise is not always easy.
That theme is at the heart of both feature articles in this issue. In certain women, finding signs of a tumor using mammography can be akin to "finding a polar bear in a snowstorm," readers learn in Laura Beil’s "To Screen or Not to Screen." Normal, healthy breast tissue sometimes looks similar to a nascent cancer. This, as Beil details, leads to a huge number of false