Antitumorigenicity

The ability of a substance to slow, inhibit or reverse tumour formation — specifically, to attenuate tumours arising in the presence of tumour promoters or carcinogens. It is assessed in vitro with cell cultures and in vivo with animal models, the latter carrying greater weight for risk assessment. The concept anchors chemoprevention research: the search for dietary strategies and compounds that lower cancer incidence before disease starts. Distinguishing it from antitumour activity matters — preventing a tumour from forming is a different claim from shrinking an established one, with different evidence requirements.