I think the other consideration is that when you're looking at what the right age is, the evidence from the NLST study is that with regard to the 55-to-74 age group and the 30 pack-year criteria, this is where the benefit occurs. So if you were to start, you would start there.
The other issue with over-screening, and we see this for other types of screening, is that we know there are populations where screening doesn't work. A lot of times it has to do with the fact that there are harms associated with it. If you look for something, sometimes you find something that's not cancer, but in order to rule out cancer, sometimes you have to put a person through a lot of what would be considered follow-up tests or biopsies and so on, which potentially put a person at risk for something.
So you want to minimize the harms of screening. You want to make sure you're not finding false positives, which would put somebody through unnecessary surgery or things like that, while still maximizing the benefits. It's always this balance of where you'll get the most benefit in the trade-off with the harms. I think as you look at other age groups or other risk factors, you have the potential, if you don't know there's a benefit, for maybe additional harms. I think those need to be considered in some of the studies.