ABSTRACT
This chapter describes the effects of hyperthermia alone, and in combination with radiotherapy and cytotoxic drugs, on multicellular tumor spheroids. In medicine, hyperthermia is known as the therapeutic use of local or systemic heating above the normal range of body temperature. In clinical medicine, hyperthermia is mainly used to potentiate the effects of cytotoxic drugs or radiotherapy. Spheroids are generally more resistant than single cells from monolayer cultures to treatment with hyperthermia alone. Tumor cells grown as multicellular spheroids show many similarities to solid microtumors in vivo. If the spheroids were separated into single cells immediately before heating, the single cells showed heat sensitivity similar to single cells grown in suspensions. The use of monolayer cultures has several disadvantages when investigating the influence of timing on treatment with hyperthermia and radiation or chemotherapy. The therapeutic effect of combined heat and radiation or chemotherapy is dependent on doses and timing of both treatment modalities.
