Randomized clinical trial on 7-day-continuous accelerated irradiation (CAIR) of head and neck cancer - report on 3-year tumour control and normal tissue toxicity

Abstract

Purpose: To evaluate tumour and normal tissues 3-year response to 7-day-a-week continuous accelerated irradiation (CAIR) compared to a conventional treatment (5 days per week) in a randomized trial.

Materials and methods: One hundred patients with squamous cell carcinoma of the head and neck in stage T(2-4)N(0-1)M(0) were entered into the trial between December 1, 1993 and June 30, 1996. Dose per fraction of 2.0 Gy (to the end of 1994), and 1.8 Gy (since January 1, 1995) was the same in both arms and delivered once a day at regular 24-h intervals to total dose in the range of 66-72 Gy (depending on tumour stage). The only difference was overall treatment time being 5 weeks in the CAIR and 7 weeks in control arm.

Results: Actuarial 3-year local tumour control was 82% in the CAIR and 37% in the control group (P<0.0001) with reduction in local recurrence rate of 83%. Actuarial 3-year overall survival was 78 and 32% (P<0.0001), respectively. Confluent mucositis was significantly more severe and lasted longer in the CAIR than in control arm. After 2.0 Gy fractions five of 23 patients (22%) in the CAIR developed early necroses over a period of 2-4 months of follow-up which can be considered as a consequential to severe protracted acute mucosal reactions (CLE). For this reason dose per fraction was lowered to 1. 8 Gy and the CLE was not observed again until now. Thus the overall rate of CLE decreased to 10%.

Conclusions: The gain in tumour control is likely the effect of shortening of overall treatment time by 14 days and regular continuous dose delivery during the whole course of radiation therapy including weekends. A 7-day schedule produces more severe acute mucosal reactions lasting longer than in conventional fractionation, however tolerable by patients. Relatively high rate (22%) of CLE in the 7-day arm observed during the first year of the study was eliminated by decreasing dose per fraction from 2.0 Gy to 1.8 Gy.