The influence of thyroid stimulation on the incidence of 3-methylcholanthrene-induced tumors

The incidence of tumors induced by a single s.c. injection of 2 mg of 3-methylcholanthrene was observed in euthyroid and thyroidectomized rats and in rats fed thyroid powder. Thyroid feeding increased the metabolic rate by a factor of 1.6 and reduced the incidence of tumors at the site of injection from 92% in euthyroid rats to 36% in hyperthyroid rats.