The reaction of the endocrine system of the rabbit to tumor inoculation and the relation of this reaction to malignancy

Abstract

Within recent years, a great deal of evidence has been accumulated from both clinical and laboratory sources which has tended to show that some kind of connection exists between the occurrence and growth of tumors and the system of organs regulating animal economy. For the most part, the evidence bearing upon this problem has been circumstantial. In a few instances a definite relationship appears to have been established as in the case of the experiments reported by Loeb 1 concerning the effects of castration on the incidence of mammary tumors in mice and those of Rohdenburg, Bullock, and Johnson 2 on the effects of operative removal of various organs upon the growth of transplanted tumors and the immunity of tumor animals. There are also therapeutic observations on the use of thyroid and of thymic products alone or combined with castration 3 which might be regarded as equally suggestive were it not for the fact that similar results have been obtained by the use of a variety of means. 4

Two years ago, we reported the occurrence of a malignant tumor in the scrotum of a rabbit infected with Treponcma pallidum. 5 Since that time, a careful study has been made of the conditions presented by this animal 6 and a long series of investigations based upon the behavior of transplanted tumors derived from this stock has been carried out which have shown that there is an essential connection between the growth of transplanted tumors and certain members of the endocrine system on the one hand, and the mechanism of animal defense on the other.

In the animal with the spontaneous tumor, there was a notable tendency to atypical epithelial proliferation in many parts of the body associated with a deficiency in the reaction of the surrounding connective tissues and a widespread tendency to degeneration. There were also very striking alterations in such organs as the thyroid the thymus, the suprarenals and the lymphoid tissues, which might have been regarded as part of a general organic deterioration attributable to one or both of the diseases present.