Hypofractionation reduces the therapeutic ratio in early glottic carcinoma

From 1969–1985 two types of fractionation schedules with similar time, dose, and fractionation factor (TDF ) values were used to treat 197 patients with Tis, TI, and T2 squamous cell carcinoma of the vocal cord. One hundred and thirty-one patients were treated with conventional daily 2.0 Gy fractions, and 66 patients were treated once per week with large (5.5–6.6 Gy) fractions (hypofractionated group); both groups were treated over a period of approximately 6 weeks. The local failure and complication rates for patients completing treatment in the two groups were compared; a patient was regarded as having suffered a serious complication of treatment if laryngectomy or tracheostomy had to be performed in the absence of active disease, or if antibiotics and/or corticosteroids had to be prescribed for laryngeal oedema and/or necrosis. In patients with Tis and T1 disease, the failure rate was worse in the hypofractionated group than in the conventionally treated group ( p = 0.06). In the smaller group of T2 patients, no significant difference was found in the failure rates between the hypo- and conventionally fractionated groups. Complication rates were similar in Tis T1 and T2 patients, but significantly higher in the hypofractionated group ( p < 0.001). Neither stage nor fractionation schedule had an effect on survival, but laryngectomy/tracheostomy free survival was significantly worse in Tis T 1 patients receiving hypofractionated treatment, ( p = 0.008) although not in T2 patients. These results indicate that in Tis T1 glottic cancer, hypofractionation of radiotherapy produces a reduction in the therapeutic ratio.