Advances in Chemical Carcinogenesis: A Historical Review and Prospective

Abstract
At the dawn of the 20th century, we had recognized that chemicals cause cancer, but we had not yet identified individual cancer-causing molecules, nor did we know their cellular targets. We clearly understood that carcinogenesis, at the cellular level, was predominantly an irreversible process. What we lacked was knowledge of the mechanisms by which chemicals cause cancer and the molecular changes that characterize tumor progression.