What Happens in Chemotherapy Malin Dollinger, MD, and Ernest H. Rosenbaum, MD Adapted for the Canadian edition by Richard Hasselback, MD The idea of treating cancer with chemical agents or medications has been around since the days of the ancient Greeks. Yet the practice of cancer chemotherapy as it's known today really only began in the 1940s. Near the end of that decade, nitrogen mustard became the first drug approved to fight tumor cells . Over the next 20 years, chemotherapy was essentially an investigational treatment. But in the last 30 years, more effective antitumor drugs have been developed, and other new