Worldwide trends in lung cancer pathology.

Molecular profiling studies serve to remind us that lung cancer is a complex disease, with different phenotypes that are characterized by variation in morphology as well as molecular composition. Over recent decades, there appear to be worldwide shifts in the relative frequencies of various phenotypic patterns of lung cancer, which are even more striking than changes in the overall incidence of lung cancer. This review summarizes major worldwide trends in lung cancer pathology, which can be explained in part, but not entirely, by changes in cigarette design. Characterizing these trends will be important for recognizing contributions of carcinogens other than tobacco smoke to the worldwide problem of lung cancer.