Response of mouse sarcoma-180 to cis-platin in combination with radiation & hyperthermia

The in vivo response of a transplantable mouse tumour, sarcoma-180, to cis-platin (cDDP, 1.0, 2.5 or 5.0 mg/kg b.wt), local hyperthermia (HT, 42 degrees C, 30' or 60' and 43 degrees C, 30') and irradiation (RT, 10 Gy) was assessed on the basis of tumour cure (complete response, CR), volume doubling time (VDT) and regrowth delay (RD) as well as animal survival up to 120 days. Each agent was given as a single modality or in different combination regimens. A single injection of cDDP produced a dose dependent increase in all the parameters. Of all the single treatments, HT at 43 degrees C, 30' gave the maximum tumour cure. Combination of any of the two treatments resulted in a better response than all the single treatments. The chemosensitizing effect of heat was more pronounced than its radiosensitizing effect. Combination of all the three modalities, cDDP (2.5 mg/kg) + RT + HT (43 degrees C, 30') resulted in 100 per cent CR, without any local recurrence. This treatment also resulted in a significant increase in 120 day tumour free survival compared to all single modality treatments and bimodality treatments, except cDDP + 43 degrees C, 30'. This study indicates a potential advantage of the trimodality approach over single and bimodality treatments in the local control of solid tumours.