TUMORIGENIC POWERS OF STILBŒSTROL AND FOLLICULAR HORMONES

Abstract

Results of experiments on the tumorigenic and hysterotrophic doses of stilbestrol are presented. To 33 castrated female guinea pigs .1-80 mcg of stilbestrol in .4 ml of olive oil were injected sc 3 times weekly for 87-115 days. The 1st evidence of a fibrous reaction at several sites appeared with 3-10 mcg of stilbestrol per injection. With 40 mcg and especially with 80 mcg per injection the tumoral reaction increased. With estradiol 100-200 mcg per injection were needed to provoke a reaction similar to that of 3-10 mcg of stilbestrol and at least 400 mcg of estradiol or of estrone were needed to obtain a reaction equal to that produced with 80 mcg of stilbestrol. The tumorigenic action of estradiol was greatly enhanced by esterification. 5-40 mcg given as estradiol monobenzoate was greater than similar quantities of stilbestrol. With 10 mcg of estradiol given as the monocaprylic ester large fibroids developed. However with 80 mcg of stilbestrol tumorigenesis was equal to that of the same quantity of estradiol given as monobenzoate. Results were tentatively explained by the inability of the organism to inactivate stilbestrol as rapidly or as effectively as estradiol or estriol. Blood loss from the genital tract of the guinea pigs was more common with stilbestrol than with the natural hormones but equal to that with the esterified hormones. Therefore stilbestrol was thought to be more toxic.