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The Influence of the Gonads and of Certain Steroid Hormones on the Growth of the Spontaneous and Transplantable Ovarian Tumor in AXC Rats

( Instituto de Medicina Experimental, del Servicio Nacional da Salud, Av. Irarrazaval 849, Santiago, Chile)

New evidence is offered that growth of the transplantable, spontaneous, granulosa-cell tumor of the AXC rat is greatly enhanced by the presence of the gonads. The latent period and survival are shorter in intact animals than in castrated ones.

This stimulating action of the gonads is due to the gonadal steroids; with the continuous absorption of testosterone, estradiol, and progesterone from subcutaneously implanted pellets, the tumor grows in castrated animals at least as rapidly as in the presence of the gonads.

With shortened survival due to the gonads or gonadal steroids, the final weight reached by the tumor at the moment of death is less than in castrated animals. This suggests that the influence of gonadal steroids on the evolution of the tumor is not simply a more rapid growth but an increased malignancy of the tumor. This effect is established in a definite manner in the course of 5–6 weeks.

Though the mechanism of the increase in malignancy through the action of gonadal steroids is still not clear, there is evidence that it is not simply a sequel of the androgenic or estrogenic potencies of these steroids, since the effect was also obtained with progesterone and pregnenolone.

The corticoids, deoxycorticosterone and cortisone, did not enhance the growth of the tumor. Cortisone caused even slower growth of the tumor than was observed in untreated castrated animals.

^* Visiting Research Associate at the Sloan-Kettering Institute for Cancer Research, New York City, until October 1956.

Received 2/ 2/56.