Enhanced effect of systemic cyclophosphamide by local tumor hyperthermia in mice

The influence of combined chemotherapy (cyclophosphamide, 25 mg/kg) and local tumor hyperthermia (42.5 degrees C for 30 minutes) followed by amputation was studied on a metastatic tumor model (Lewis lung carcinoma) injected into the footpad of BDF1 mice. The tumor was found to be sensitive to heat treatment. Neither local tumor heating nor chemotherapy improved life span when "singly" combined with later surgery. However, combined chemotherapy and local tumor heating followed by later surgical removal of residual tumor did show a significant improvement of survival (P less than 0.01). Possible explanations are commented on.