Strain C57B1 mice in which thymic lymphosarcomas had been induced with total-body X-radiation were treated, at various times in the course of tumor development, with either hydrocortisone or local X-irradiation. Their survival was compared with that of placebo-treated controls. In other sacrificed control groups, the incidence and extent of lymphoma development at the time of treatment was established by microscopic examination.
Treatment with single massive doses of hydrocortisone or local thymic X-irradiation at 50 or 100 days after lymphoma induction resulted in permanent cure of half or more of the animals. For a given dose, hydrocortisone was equally effective when given at any time interval up to 100 days after the start of lymphoma induction. However, the therapeutic efficacy of hydrocortisone was a significant function of hormone dose, over the range 0.3 to 3.0 mg. In addition to the cure of many animals, significant prolongation of life was noted in animals dying of lymphomas in all of the treated groups.