It's only been in the past few years that we have begun to appreciate that there may be many different subgroups of patients who fit within the broader lung cancer population. We now have begun to see differences in the safety and/or activity of certain drugs in never-smokers vs. smokers, patients with adenocarcinomas (and especially bronchioloalveolar carcinoma, or BAC)vs. squamous cell carcinomas or other subtypes, and even in women compared with men.