Influence of local hyperthermia combined with radiation on tumor growth and lung metastases of transplantable Lewis lung carcinoma growing in hind legs

: The influence of combination of local hyperthermia and radiation on tumor growth and metastases was studied using Lewis lung carcinoma. Tumors growing intramuscularly in the right hind legs of C57BL/6 mice were irradiated at 10 Gy of radiation dose and immersed in a water bath. Time and number of development of metastases were determined according to size and number of lung colonies at 19 days after tumor implantation. Local hyperthermia at 42.8, 43.3 or 43.5 degrees C for 30 min immediately after or before irradiation enhanced the growth delay of tumor with irradiation or with hyperthermia alone. Development of metastases several days after heating was also inhibited by the combination of heating and irradiation. These effects were diminished with hyperthermia applied 3 hr or more after irradiation. Promotion of metastases around the time of heating by severe hyperthermia with above 43.3 degrees C alone was not inhibited by combination with radiation, regardless of their sequence. Radiation had no effect on the number of metastases developed by the heating. However, irradiation 48 hr or more before severe heating reduced the number of metastases developed by the heating.