The potential harms listed here are more than offset by this one important benefit. But that calculation changes if we stop focusing on those patients at very high risk of disease. For everyone else, the risks may outweigh the gains, and the overall cost in dollars would be prohibitive.
Insurance doesn't cover the test, and the NCI says that a scan costs about $300. But when I called about 50 places around the country, I heard numbers more like $1,800, with Sequoia Hospital in Redwood City topping the charts at $4,000. (Update, Nov. 29, 2010: The Bonnie Addario Foundation reports that a research study on lung cancer screening at Sequoia Hospital charges high-risk patients $399 out of pocket for the procedure.) To put this in perspective , there are about 7.5 million people in the United States at high risk of lung cancer like those the NCI studied. The price tag for screening all of them once would be at least $2 billion, and more like $13 billion if the prices I found are more accurate.
But the new round of CT scan advertisements released following the Nov. 4 press conference target a much larger population for screening. The Bonnie Addario Foundation's criteria suggest that some 46 million people should be screened at a cost of between $14 billion and $84 billion (about the budget of the U.S. Department of Education). Beverly Hills Radiologists? It says 77 million people and $23 billion to $138 billion (similar to the numbers for the Department of Labor). And if you go with St. Joseph's in Atlanta, which encourages screening for nonsmoking women and all men with any smoking exposure whatsoever, that's 166 million people—about half the U.S. population, at a cost of around $50 billion to $300 billion (half the Medicare program).
All of this would be for the first scan. Then there are the follow-up tests associated with false positives. If we stick to screening the high-risk people it will probably be worth it. Researchers at the Massachusetts General Hospital in Boston reported that it would cost around $150,000 for each quality-adjusted life year saved if we focused on screening those particular people. That's much more costly than, say, mammography, but it's in the neighborhood of many other cancer treatments. Still, these researchers noted that more could be gained at lower cost by getting people to stop smoking. Those who quit their habits reduce their risk of getting lung cancer by about 50 percent, which is more than double the benefit of being screened, without any of the radiation, false positives, overdiagnoses, and unnecessary surgeries.
Some day CT screening will save lives—hopefully a lot of them. It will harm some people, too. We can stay ahead in this tradeoff if we are circumspect about whom we screen, and if we don't believe every radio ad we hear.