Dr. Hoover: For the most part, the methods in human populations are quite similar. There are some specific methods that are different. For example, family studies are used to identify high penetrance genes-the genes that are responsible for familial cancers. But, these kinds of studies are not very productive for studying environmental exposure because most families tend to have the same environmental exposures. Outside of that, trying to evaluate the impact of natural genetic variation in the population on cancer risk is very similar to looking at environmental exposures. It's essentially another exposure--you are exposed to a particular version of a gene.

One difference, however, is a difference in scale. In environmental studies, we worry about confounding exposures. So, if you're investigating coffee drinking, you have to control for the effects of tobacco because they usually correlate. But, there are usually a limited number of confounding factors that you know about or that you can assess. With the new genetic technology, there is a new possibility that if you're interested in a particular gene, there may be thousands of others whose effects you may be called upon to control for. This does serve up a kind of challenge of scale that we haven't seen before. In general, however, the principles are largely similar and transferable.