Systemic thermochemotherapy in a rat model.

Abstract

The purpose of this study was to determine the effects of systemic hyperthermia, with and without Adriamycin, on two rat tumour models. Fischer rats were implanted subcutaneously with either a methylcholanthrene-induced sarcoma or a transitional cell carcinoma. In the first experiment, 32 rats with tumour volumes of 1 cm3 were divided into four groups of 8 rats receiving: (a) Adriamycin alone (2 mg/kg intraperitoneally) (group 1), (b) systemic hyperthermia alone (water bath immersion to a rectal temperature of 41.5 degrees C for 30 minutes) (group 2), (c) Adriamycin and systemic hyperthermia (group 3) or (d) immersion in water bath at 37 degrees C for 30 minutes (control group) (group 4). Serial tumour volume and animal survival were monitored. No differences were seen among the groups in either tumour system. In a second experiment, an identical protocol was used except that each animal received its respective treatment three times, at weekly intervals. In the rats implanted with methylcholanthrene-induced sarcoma, tumour volume was lower in group 3 than in control group 4, beginning at day 23 (37.5 +/- 8.2 cm3 vs. 52.3 +/- 9.6 cm3 [p less than 0.05]). Systemic hyperthermia or Adriamycin alone did not alter tumour growth in relation to the control group. In the transitional cell carcinoma system, tumour volume was decreased in both groups 1 and 3 at day 35 (group 1 = 32 +/- 5.4 cm3, group 3 = 28.1 +/- 12 cm3 vs. group 4 = 48.8 +/- 9 cm3 [p less than 0.05 for each]). Adriamycin with systemic hyperthermia was no more effective than Adriamycin alone. Tumour growth was similar in groups 2 and 4. These data demonstrate that multiple treatments with Adriamycin and systemic hyperthermia were effective in decreasing the rate of tumour growth in rat tumour models, whereas a single exposure had no effect.