Azathioprine induction of lymphomas and squamous cell carcinomas in rats.
The carcinogenicity of azathioprine was evaluated in weaning female noninbred Sprague-Dawley rats by feeding it in the diet. Due to toxicity, the dose had to be changed during the course of the experiments and ranged from 0.015 to 0.04% of the diet by weight. In the first experiment, the estimated maximal cumulative consumption of azathioprine was 1.5 g/rat. Of the 14 rats evaluated, six developed thymic lymphomas, and four developed squamous cell carcinomas of the ear duct. When the experiment was repeated with a slightly lower daily consumption but with a cumulative total dose of 2.2 g/rat, there were seven of 19 rats with thymic lymphoma and two rats with ear duct carcinoma. These data support the hypothesis that azathioprine is a carcinogen.
D000818:Animals; D001379:Azathioprine / Q000633:toxicity; D002294:Carcinoma, Squamous Cell / Q000139:chemically induced*; D004428:Ear Neoplasms / Q000139:chemically induced; D005260:Female; D008223:Lymphoma / Q000139:chemically induced*; D051381:Rats; D011919:Rats, Inbred Strains; D013953:Thymus Neoplasms / Q000139:chemically induced
D001379:Azathioprine