Nicotine and estrogen metabolism--possible implications of smoking for growth and outcome of treatment of hormone-dependent cancer? Discussion of experimental results.

The combination treatment of hormone-dependent autochthonous mammary carcinomas in the rat with nicotine plus HECNU, a water-soluble nitrosourea, resulted in a potentiation of antitumor action. Nicotine and its metabolite cotinine are strong inhibitors of the aromatase. With regard to investigations in smoking women, suggesting a decreased endogenous estrogen production, our results indicate that smoking might influence growth and treatment results of hormone-dependent human cancer.