Effect of hyperthermia on human melanoma cells heated either as solid tumors in athymic nude mice or in vitro

Human melanoma cells were exposed to clinically acceptable hyperthermia (42.5 degrees C) either as solid tumors in athymic nude mice or suspended in culture medium. Single cell survival was in both cases assayed in vitro in soft agar. The response to heat varied considerably among the five melanomas studied. The D0-values ranged from 21 to 590 min when the cells were heated in vitro. The response to heat following treatment in vivo was for a given melanoma larger than that following treatment in vitro. However, cells which were resistant to heat treatment in vitro, were also resistant to treatment in vivo, and those which were sensitive in vitro were also sensitive in vivo.