The effect of mixed fractionation with X rays and neutrons on tumour growth delay and skin reactions in mice.
We have compared the effects of mixed fractionation schedules with X rays and neutrons on growth delay of a murine tumour and skin reactions in mice. The schedules were five daily fractions of X rays, neutrons or mixtures (NNXXX, XXXNN or NXXXN). For clamped tumours or skin all three mixed schedules had the same effect. In contrast, for unclamped tumours giving the neutrons first (NNXXX) was more effective than the other two mixed schedules. This represented a true therapeutic gain and implies that if neutrons are used clinically as only part of a course of fractionated radiotherapy, they should be given at the beginning rather than at the end of treatment.
D000818:Animals; D002455:Cell Division / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D051379:Mice; D008808:Mice, Inbred CBA; D009502:Neutrons; D012513:Sarcoma, Experimental / Q000532:radiotherapy*; D012867:Skin / Q000528:radiation effects*; D012878:Skin Neoplasms / Q000532:radiotherapy; D014965:X-Rays