Tolerance to accelerated fractionation in the head and neck region

To improve efficacy of radiotherapy in head and neck carcinomas, shortening the treatment time by accelerated fractionation is one possible method. However, there is a risk of enhancing side-effects. To study the tolerance to accelerated fractionation a study was thus performed where 2.0 Gy/fraction was given twice daily with 7-8 h interval between fractions. The total dose was 60 Gy and the overall treatment time 19-22 days. Thirteen patients with tumours in the head and neck region were consecutively included in the study. The treatment volumes ranged from encompassing the primary tumour with a margin to including the oral cavity and neck nodes bilaterally. Evaluation has been done by means of scoring the mucosal reactions, subjective estimation of pain, and functional impairment. Furthermore, the late radiation effects have been assessed by scoring of telangectasia, fibrosis of subcutaneous tissues and necrosis. The median follow-up time was 37 months. The treatment was generally well tolerated and could be completed without interruptions. However, in most cases the acute mucosal reactions appeared to be severe for a longer time than after standard fractionation. Restitution of normal mucosa without persistent complications has been achieved in all cases. The toxicity of this treatment schedule seems to be acceptable. No severe late complications have occurred during the follow-up period. A comparison with other treatment schedules has been made, using the linear-quadratic (LQ) model to calculate biologically effective dose (BED). In the present schedule it is shown that the early reacting normal tissue and tumour effects are predicted to be similar to the EORTC schedule whereas the late effects would be less pronounced. The CHART protocol gives less effects on early responding tissues due to the low total dose.