THE HORMONES IN HUMAN REPRODUCTION 



cancer-producing (carcinogenic) substances that are also 

 estrogenic. It becomes therefore a burning question, whether 

 or not the familiar and commonly known estrogens are 

 carcinogenic. This question cannot be answered "no" or 

 "yes" without explanation. Briefly the situation is as fol- 

 lows : The estrogens commonly used in medical practice and 

 in the laboratory do not ordinarily produce cancer by their 

 own direct action. In experimental animals cancer may fol- 

 low their use under special circumstances, of which the 

 following is a good example. In a certain pure-bred strain 

 of mice, the females have a high tendency to develop cancer 

 of the mammary glands. The males inherit the same tendency 

 but do not suffer from it because the male mammary gland 

 is too scanty to become cancerous. If the males are given 

 large doses of estrogenic hormone, their mammary glands 

 grow larger and then they often develop cancer of the 

 breast. 



In our Carnegie Embryological Laboratory, Hartman 

 and Geschickter have given sixteen Rhesus monkeys enormous 

 doses of estrogenic hormones over periods of many months, 

 even for two or three years, and have not found a single 

 tumor. On the other hand Alexander Lipschiitz of Santiago, 

 Chile, with Rigoberto Iglesias, Luis Vargas Fernandez and 

 others has found that in guinea pigs it is very easy to produce 

 fibrous tumors in the abdominal cavity with estrogens. These 

 are not malignant but may kill the animal by their mere size. 

 There is even a recent report (from Gardner and E. Allen 

 of Yale) of tumors of the uterus in mice, which may be 

 malignant, produced by injection of estrogenic hormones in 

 non-cancerous pure-bred strains. 



The present definite medical consensus is that in human 

 beings cancer is not produced by ordinary doses of estrogens. 

 The whole subject, however, demands and is getting further 

 investigation. 



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