Only a few years ago, oncologists saw lung cancer as divisible into small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC), with very little relevance to any division beyond that point.

I had the opportunity to sit down with Dr. Matthew Horton, a pathologist who works with my own group at Swedish Cancer Institute in Seattle, at a pathology company called CellNetix. He did subspecialty training in lung pathology and is a terrific resource for my colleagues and me, and now for a wider audience.

In most of the history of lung cancer management, we have been "lumpers" rather than "splitters", tossing together many different kinds of lung cancer together and presuming that they all respond similarly and should be treated similarly.