TREATMENT DURATION AS A PROGNOSTIC FACTOR FOR LOCAL-CONTROL AND SURVIVAL IN EPIDERMOID CARCINOMAS OF THE TONSILLAR REGION TREATED BY COMBINED EXTERNAL-BEAM IRRADIATION AND BRACHYTHERAPY

Purpose: We wanted to study the influence of the time factor in a comb ination of external irradiation and brachytherapy from a retrospective study of 370 squamous cell carcinomas of soft palate and tonsil. Pati ents and methods: From 1977 to 1993, 370 soft palate and tonsillar car cinomas were treated at the Centre Alexis Vautrin. All patients receiv ed external irradiation (ERT) with a minimum dose to the tumour of 45 Gy, followed by low dose rate brachytherapy by Iridium 192 using the t echnique of plastic tubes; 22 patients received neo-adjuvant chemother apy. We treated 85 T1, 159 T2, 117 T3 and nine T4 or TX carcinomas; 12 8 of these had palpable nodes. There were 267 men and 24 women. The me dian age was 55 years (range 33-81 years). Results: The median duratio n of the total treatment was 57 days. The rate of local control was 88 % at 5 years when the treatment time was 7 weeks and 74% when it was 9 weeks (P = 0.001). The rates of overall survival at 5 years were 63 a nd 44%, respectively (P < 0.0001). For the interval between external i rradiation and brachytherapy the series was divided into three groups, i.e. patients treated with a delay inferior or equal to 16 days (2 we eks), patients for which the interval was between 16 and 20 days and p atients treated with a delay greater than 20 days (3 weeks). The rates of local control and overall survival at 5 years were not significant ly different in the two first groups so we amalgamated these two group s and compared them with the third group. In this way the time cut-off for the delay between external irradiation and brachytherapy was 20 d ays. At 5 years, the rate of local control was 85% for the group for w hich the interval was inferior to 3 weeks and 73% when the delay was g reater (P = 0.01). The rates of overall survival at 5 years were 59 an d 38%, respectively (P < 0.001). Multivariate analysis confirmed that protraction of treatment was a factor for poorer local control. This f actor was independent of the other prognostic factors. Conclusion: The total duration of irradiation and the delay between external irradiat ion and brachytherapy were significant prognostic factors for local co ntrol and overall survival of soft palate and tonsil carcinomas. The o verall duration should not be greater than 7 weeks (external irradiati on, 5 weeks plus a delay of 12-15 days between ERT and brachytherapy). The delay should never be greater than 20 days, but a boost should be considered to make up for the loss of local control. (C) 1997 Elsevie r Science Ireland Ltd.