Laryngeal carcinoma: treatment interruption and outcome

Two patient groups have been identified from a data base of 965 patients with carcinoma of the larynx. One group of 393 patients had squamous cell carcinoma of the larynx arising in the glottis--no nodal involvement; the other group of 163 patients had tumours arising in the supraglottic region. The second group was a more heterogenous group some patients had nodal involvement at the time of presentation. All patients were treated on a linear accelerator. Patients were treated using a variety of dose-fraction-time schedules. Mathematical modelling using linear quadratic equation was carried out. This shows that a break in treatment if a week reduces the local tumour rate for glottic tumours by 12% or about 25 per day. Local tumour control rates increased as the effective dose was increased. The data for tumours arising in the supraglottic region is not so convincing though it does show that prolongation of treatment time reduces local tumour control rates. The effects of longer times can be nullified by increasing the effective dose. The supraglottic subject, however, is very heterogenous, and the groups within the subset are small.