Therapeutic efficacy of long duration-low temperature whole body hyperthermia when combined with tumor necrosis factor and carboplatin in rats

This study examines the effects of a combined modality regimen of long duration-low temperature whole body hyperthermia (6 h at 40.0 degrees C; LL-WBH), recombinant human tumor necrosis factor-alpha (TNF) and carboplatin (CBDCA) on a transplantable fibrosarcoma as well as normal tissue. We compare LL-WBH with short duration-high temperature whole body hyperthermia (2 h at 41.5 degrees; SH-WBH). LL-WBH alone had no significant effect on tumor growth. Tumor growth delay (TGD) with TNF alone (0.1 days) and that with CBDCA alone (1.3 days) were significantly increased to 2.6 days (P < 0.05) and 2.8 days (P < 0.05), respectively, when combined with LL-WBH. Although TNF+CBDCA produced minimally increased TGD of 1.9 days, the combination of LL-WBH+TNF+CBDCA produced a significantly greater TGD of 5.6 days, compared to the other dual combinations (P < 0.01). There was no difference between TGDs for SH-WBH and LL-WBH in combination with TNF+CBDCA. Trimodality treatment-induced normal tissue toxicities, characterized by body weight loss, diarrhea, foot edema, and myelosuppression, were significantly greater in rats treated with SH-WBH+TNF+CBDCA, compared to LL-WBH+TNF+CBDCA. Histopathological examination also demonstrated that SH-WBH+TNF+CBDCA caused severe damage to the lymphoid tissues, intestinal tract, and peripheral microvasulature. We observed minimal histopathological changes observed in rats treated with LL-WBH+TNF+CBDCA. These data suggest that LL-WBH in combination with TNF and CBDCA has a greater therapeutic efficacy than SH-WBH.