Background and purpose: An analysis of the 366 patients treated with conventional radiotherapy in the CHART randomized trial was performed to determine whether prolongation of treatment time had any influence on tumour control or survival and to assess if this could have influenced the results of the randomized comparison of CHART against conventional radiotherapy.
Method: After a preliminary analysis the cases were divided into two groups according to duration of treatment.
Results: Survival and primary tumour control showed small margins of deterioration when the 232 patients who had been treated up to 48 days were compared with 127 patients who had been treated in 49 or more days. These differences were not large with an estimated difference in 2-year survival of 8% and not conventionally statistically significant (P=0.25); furthermore, the survival difference was considerably reduced when the prognostic factors were taken into consideration in a Cox model.
Conclusion: With a mean difference in treatment duration of 5.8 days, the marginal differences observed between patients treated for longer and shorter times are compatible with that which has been suggested in previous publications for the prolongation of treatment time in head and neck cancer. We conclude that the randomized comparison of CHART with conventional radiotherapy is unlikely to be affected by conventionally treated patients who took longer than 48 days to complete their treatment.