Carcinogenicity studies of inhaled cigarette smoke in laboratory animals: old and new.

A new study demonstrates that lifetime whole-body exposure of B6C3F1 mice to high doses of cigarette smoke robustly increases lung cancer incidence compared with sham exposed animals. This is the first study to demonstrate a strong effect of inhaled cigarette smoke on lung cancer in an animal model. This commentary attempts to put the new results in perspective with the existing literature on cigarette smoke inhalation studies in animals and discusses strengths, limitations and possible applications of available models.