The significance of fractionation regimens in radiation and combined hyperthermia using a murine fibrosarcoma.
The significance of time-dose relationships in the use of local tumor hyperthermia (LTH) when combined with radiation (RAD) was studied in a murine fibrosarcoma. RAD, either alone or combined with LTH, was delivered in four equal fractions (total doses, 1.8 to 4.2 krad) separated by 1 to 4 days. LTH (43.1 C +/- .05 C for 15 minutes, water bath) was applied immediately after RAD. In this tumor system, RAD was most effective when delivered every 2nd or 3rd day, by a factor of 1.25 over the response achieved when the four fractions were delivered every 1 or 4 days. At all levels studied, RAD + LTH produced a superior tumor response compared to RAD alone. The ratio of the RAD + LTH/RAD doses to achieve an isobiological response ranged from 1.7 to 2.5. Most significant was the finding that the RAD + LTH treatment response was independent of the fractionation scheme used and more dependent on the total RAD dose delivered.
D000818:Animals; D004307:Dose-Response Relationship, Radiation; D005354:Fibrosarcoma / Q000628:therapy; D006979:Hyperthermia, Induced; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D011836:Radiation Tolerance; D012513:Sarcoma, Experimental / Q000628:therapy*; D013997:Time Factors