Timing of combined hyperthermia and 1,3-bis(2-chloroethyl)-1-nitrosourea or cis-diamminedichloroplatinum in BD IX rats with BT4A tumours.

Groups of 7-10 evaluable BD IX rats with the neurogenic BT4A tumour on the right hind leg were treated with waterbath hyperthermia (44 degrees C, 60 min) in combination with 1,3-bis (2-chloroethyl)-1-nitrosourea (BCNU) 20 mg/kg or cis-diamminedichloroplatinum (cis-DDP) 3 mg/kg i.p. at different sequences and timing within +/- 24 hr. Tumour responses were evaluated by tumour doubling time and clinical criteria, toxicity by toxic deaths, weight loss, and local skin reactions. With both BCNU and cis-DDP, tumour response was markedly dependent on timing; the greatest effects were obtained giving hyperthermia just after the drug. Local side effects were not different in the timing groups, but cis-DDP general toxicity was most severe when cis-DDP was given just before hyperthermia.