It is assumed that this treatment regimen will not be of further interest if the true response rate is less than 32.6% (Po0.326). It is also assumed that a true response rate of 53% or more (P10.53) would be of considerable interest in the treatment of recurrent head and neck cancer. The type I error (the probability of rejecting the hypothesis that the proportion responding to the treatment is less than or equal to Po when this hypothesis is actually true) is 0.05.