Abstract
Biological evidence supporting the effectiveness of hyperfractionation, accelerated fractionation and accelerated hyperfractionation was discused in the treatment of head and neck cancers. A number of clinical trials on altered fractionation schedule have shown an improvement in the local control of advanced head and neck cancers. Despite of the clinical improvement, altered fractionation has a limitation for the local control of large tumors caused by increased in situ cellular radioresistance rather than large number of tumor cells. This was shown by multivariate analysis of the data on cervical lymph node-metastases.
