One of the most controversial issues in cancer during recent months has surrounded the question of screening (check out my screening post earlier this summer). The question seems simple enough: Does screening save lives? Ask most cancer patients and they'll say it does, but research says not so fast.With the exception of colorectal, cervical, and breast cancers, research shows that current screening tests don't spare lives and can even be harmful in some cases. So why don't most tests work? What's a person to do if they want to be proactive about early detection? Well, it's complicated. Before you read any further, throw conventional wisdom out the door. Then check out the fall issue's "Life Preserver?" from contributing writer Laura Beil and "Cancer Screening" by Dr. Barnett Kramer, of the National Institutes of Health.Among other things, these articles examine a fascinating trend called lead-time bias. Put simply, we get the false impression that we're living longer because screening diagnosed cancer early, when, in fact, the date of death doesn't change. Beil writes: "Think of it this way: Imagine an asteroid is hurtling toward Earth, with impact at noon tomorrow. Satellites from an early warning system could have discovered it a year ago and tried to destroy it, giving a year's 'survival' with the asteroid. More sophisticated technology may have found it farther out in space, say seven years ago, giving seven years of 'survival' with the asteroid. Either way--a one-year survival or a seven-year survival--still means calamity at noon. Early detection didn't mean we lived longer; it just meant we knew sooner, and tried harder to stop it. Or we were working feverishly to stop it, and some other global cataclysm occurred first."With all the screening tests that are currently available, if we know what doesn't save lives, why not focus on finding something new that does? The Canary Foundation, a nonprofit dedicated to early cancer detection, is making some interesting headway in this area (read more about the kind of research they're doing in "Screen Savers").For now, there are a number of resources available to help you better understand the potential benefits and harms of a variety of cancer screening tests. This is a topic many are passionate about, and we welcome your comments.