[Intratumoral levels and metabolism of 4-hydroxytamoxifen after percutaneous administration at the breast level].

(3H)-4 hydroxytamoxifen (4O H Tam), the active metabolite of the antiestrogen tamoxifen (Tam) was dissolved in ethanol and locally percutaneously administered on 4 human breast carcinomas before surgery. 12, 24, 72 hrs. and 7 days later, (3H)-4O H Tam was recovered in cytosol and nuclear fractions of the tumor. Only traces of radioactivity were recovered in plasma. From these results it appears clearly that the percutaneous administration of 4O H Tam on the mammary gland yields a local antiestrogen effect without the systemic effects observed in case of oral administration of Tam.