Compounds that increase the probability of tumour formation when applied after administration of a primary carcinogen, although not themselves considered carcinogenic. The concept arose in experimental studies on rodents and the best-known agent was croton oil in which the active ingredients were phorbol esters (hence their curious misnomer as ‘tumour promoting activity’). They differ from cocarcinogens which are only active when administered concurrently with the primary carcinogen, although the distinction is rarely made. Most tumour promoters are probably carcinogens if tested more thoroughly, and may contribute to tumour progression.
Subjects: Medicine and Health.