Tumor growth enhancement and systemic responses of Ehrlich ascites carcinoma following intermittent whole body hyperthermia.

Intermittent whole body hyperthermia 42 degrees C (WBH(I) administered for 30 min daily during 7 days caused significant enhancement of the growth of Ehrlich ascites carcinoma. The tumoricidal effects of hyperthermia were evident from the cytological picture as well as from the increased activity of lysosomal enzyme of the tumor cells. Elevated plasma corticosteroid levels, adrenal hypertrophy, thymus involution and lymphocytopenia were observed in both normal and tumor bearing mice exposed to hyperthermia. The alterations were more marked in the tumor bearing groups. Withdrawal of treatment caused gradual restoration of stress effects. It appears that the tumoricidal effects of WBH(I) were counteracted and surpassed by the growth stimulatory effects induced probably by hormone mediated immunosuppression.