TREATMENT RESULTS RELATED TO DIFFERENT FRACTIONATION SCHEMES AND BED EQUIVALENTS IN LOCALLY ADVANCED ORAL CAVITY AND OROPHARYNGEAL CARCINOMAS

Regarding resectability and reconstruction difficulties in the surgical management of locally advanced oral cavity and oropharyngeal carcinomas definitive radiotherapy is often the treatment of choice. Different fractionation schemes and concomitant chemoradiotherapy are still under evaluation because the results of conventional fractionated radiotherapy are not satisfactory. In this study, 37 patients treated between August 1991 and december 1996 using conventional (20 patients) and different fractionation schemes (17 patients) were evaluated regarding the BED (Biologic Effective Dose) equivalents and its effect on response rates, survival and side effects. Conventional treatment consisted of 70 Gy in 7 weeks, while it was 72-70 Gy in 6 weeks in altered fractionated treatment. For early and late effects, BED10Gy and BED3Gy were 84 Gy and 116.2 Gy in conventional, 80.68 Gy and 100.94 Gy in the concomittant boost and 82.28 Gy and 100.72 Gy in hiperfractionated group respectively. Kisquare test and Kaplan-Meier survival estimate were used for the statistical analysis. Tumor response rate, 2 years survival and late side effects were similar, only serious acute side effects were increased in the altered fractionated group. The results of this preliminary study suggests that altered fractionation schemes enhances serious acute side effects. Although BED equivalents were advised for better understanding of biologic effects in the literature relationship between the side effects and the BED equivalents could not be defined in this study.