Absence of whole body hyperthermia effect on cisplatin distribution in spontaneous canine tumors

This study was conducted to evaluate the effect of whole body hyperthermia (WBH) on cisplatin (CDDP)-derived platinum (Pt) disposition in tumor and normal tissue in dogs with spontaneously arising neoplasia undergoing conventional pretreatment diuresis.

Cisplatin was administered to 12 dogs with terminal stage, metastatic neoplasia. Cisplatin (50 mg/M2 over 1 h) was administered following 4 h of forced fluid diuresis (0.9% saline at 10 ml/kg/h). Six of the 12 dogs underwent a WBH procedure (42 degrees C rectal temperature x 90 min) simultaneously with CDDP infusion. Dogs were euthanized following the CDDP infusion, and samples from critical organs, tumor, and normal tissue adjacent to the tumor were immediately collected.

No significant differences existed between groups in serum or normal tissue Pt content. Thirty-eight tumor samples were obtained from 27 tumors in the six dogs included in the normothermic group and 43 tumor samples were obtained from 29 tumors in the six dogs undergoing WBH. Tumor volume varied from 0.08 cm3 to 2270 cm3 and multiple samples were obtained from tumors greater than 3 cm in diameter. Twenty-five paired tissue samples of tumor and adjacent normal tissue were collected from dogs in the normothermic group and 31 paired samples were obtained from the hyperthermic group. No differences were observed between groups in tumor Pt content or in the tumor/normal tissue Pt ratios.

Pt disposition was unaffected by WBH under conditions reported in this study. A forced diuresis is necessary to clinically administer CDDP at maximally tolerable doses. This maneuver results in increased blood flow to critical normal tissue that seemingly obviates any hyperthermia-induced alterations in drug disposition.