On the promoting influence of heated tumor emulsions on tumor growth

We have on several occasions presented to this Society some of the results of the study of a transplantable sarcoma of the rat, and we wish to-day to record an effect on the growth of the tumor which is produced by inoculation of the rats with an emulsion of the tumor cells, previously heated for half an hour to 56° C. This emulsion was injected into the peritoneal cavity and the fragments of living tumor are introduced beneath the skin. The promoting effect on the growth of the tumor fragments to be described became evident in several sets of experiments in which the same emulsion (unheated), blood serum, bouillon, salt and Ringer solutions were injected in the same manner, with which substances this promoting effect was not obtained. If the inoculation of the fragment of the tumor is made twenty four hours after the injection of the unheated emulsion, no difference is noted between the control rats, the rats injected with the other substances, and those injected with heated emulsion. But if the fragments are inoculated ten or more days (up to thirty days) later, then the number of tumors which develop in the rats receiving the heated emulsion tends to exceed the controls and the other series mentioned; they grow with greater rapidity so as to reach double the size of the controls or even a still greater size, and show a far smaller percentage of recoveries (retrogressions). This promoting influence is present, as stated, on the tenth day after inoculation, and indications exist tending to show that it is less effective at the expiration of thirty days. 011 the other hand, indications also exist tending to show that if the injections of heated emulsion are repeated once or twice at ten-day intervals, the conditions of the animal favoring the growth and persistence of the tumors can be maintained and possibly even still further increased.