A survey of 480 oncologists published in the December 2012 issue of the Journal of Clinical Oncology showed that they get paid more when they administer and sell chemotherapy and other drugs to their patients. This has been previously shown to account for up to 65% of their income in some instances. Yet only 27% of these oncologists acknowledged this was true for their practices.
The problem with this, of course, is that there would be a temptation to overtreat with drugs that are expensive and perhaps not especially beneficial.