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, T1, 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 less than 0.001). Neither stage nor fractionation schedule had an effect on survival, but laryngectomy/tracheostomy free survival was significantly worse in Tis/T1 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.
Harrison
D
D
Section of Radiation Oncology, Peter MacCallum Cancer Institute, Melbourne, Victoria, Australia.
Crennan
E
E
Cruickshank
D
D
Hughes
P
P
Ball
D
D
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002294:Carcinoma, Squamous Cell / Q000532:radiotherapy*; D005260:Female; D005931:Glottis; D006801:Humans; D007822:Laryngeal Neoplasms / Q000532:radiotherapy*; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011878:Radiotherapy / Q000009:adverse effects; D011879:Radiotherapy Dosage