Combined radiation and hyperthermia: effects of the number of heat fractions and their interval on normal and tumour tissues.
The effect of one or more heat treatments at 43 degrees C combined with conventional multifraction irradiation was studied in murine normal and tumoral tissues. The endpoint of this study was the TCD50 of the C3H mammary carcinoma, inoculated into the foot. For normal tissue the reaction of the skin of the foot was assessed according to a graded scoring system. Twenty X-ray fractions delivered in 20 or 26 days were combined with one, four or eight fractions of quasi-simultaneous or sequential hyperthermia (i.e. heat applied 4 h after irradiation). Tumour dose-response curves show a decrease in TCD50 and in increase in TER linked to the increasing number of heat sessions. A qualitatively similar effect of the number of sessions was observed for the different protocols (quasi-simultaneous and sequential) and for the two overall times. No significant difference was measured between one and four HT sessions plus 20 fx of RT in the normal tissue damage, while a slight difference was observed between one, four and eight HT sessions delivered with 20 fractions of RT in 26 days.
Marino
C
C
Department of Biological and Health Effects, ENEA CRE Casaccia, Roma, Italy.
Cividalli
A
A
D000818:Animals; D003131:Combined Modality Therapy; D005069:Evaluation Studies as Topic; D005260:Female; D006979:Hyperthermia, Induced / Q000009:adverse effects / Q000379:methods*; D008325:Mammary Neoplasms, Experimental / Q000532:radiotherapy* / Q000628:therapy*; D051379:Mice; D008809:Mice, Inbred C3H; D008811:Mice, Inbred DBA; D011833:Radiation Injuries, Experimental / Q000209:etiology; D012867:Skin / Q000293:injuries / Q000528:radiation effects; D013997:Time Factors