Synergism between hyperthermia and cyclophosphamide in vivo: The effect of dose fractionation

Abstract

The synergistic anti-tumor interaction between heat and cyclophosphamide (CP) was investigated. Synergism between local hyperthermia (42.5°C, 30 min) and CP was observed in mice bearing the Lewis lung carcinoma tumor in their hind leg. Local hyperthermia reduced the CP dose needed for cure or a specific tumor growth delay. CP was less effective when given in fractions. A fractionated dose regimen was more effective than CP alone when combined with heat. The thermal enhancement ratio was larger when CP was administered in more than three fractions. It is concluded that combined heat and CP chemotherapy of cancer may be clinically feasible.