Effect of estrogen treatment on DMBA-induced mammary tumor growth and biochemistry in intact and diabetic rats (38535).

Sixty percent of DMBA-induced mammary tumors in Sprage-Dawley rats regress after the animals were made diabetic by treatment with streptozotocin. Administration of estradiol valerate, 1 mg/wk/animal, caused regression of 75% of tumors in intact rats but regression of all tumors in diabetic rats. Estrogen treatment appeared to enhance the effects of diabetes, which by itself resulted in decreased activities of glycolytic enzymes. A role of insulin in growth of DMBA-induced mammary tumors may be warranted.