INFLUENCE OF TUMORAL, RADIOBIOLOGICAL, AND GENERAL FACTORS ON LOCAL-CONTROL AND SURVIVAL OF A SERIES OF 361 TUMORS OF THE VELOTONSILLAR AREA TREATED BY EXCLUSIVE IRRADIATION (EXTERNAL-BEAM IRRADIATION PLUS BRACHYTHERAPY OR BRACHYTHERAPY ALONE)

Purpose: To evaluate statistically the factors influencing the therape utic results. Methods and Materials: A statistical study was carried o ut concerning 361 patient's treated from 1977 to 1991 for velotonsilla r carcinoma. They received either brachytherapy alone (18) or a combin ation of external beam irradiation and brachytherapy (343 patients) us ing an afterloading iridium technique in plastic tubes. The distributi on of patients according to the localization was: 128 tonsils, 134 sof t palates, 9 posterior pillars, 63 anterior pillars, and 27 glossotons illar sulcus. The patients were staged as follows: 90 T1, 141 T2, 119 T3, 2 T4, 9 Tx with 230 N0, 93 N1, 9 N2, 20 N3, and 9 Nx. Results: The results at 5 and 10 years show: local control 80% and 74%, locoregion al control 75% and 70%, overall survival 53% and 27%, specific surviva l 63% and 52%, respectively. The univariate study shows at 5 years a b etter local control for T1T2 (87%) compared with T3 (67%) with p = 0.0 0004. The locoregional control is better for N0 (80%) than for N+ (55% ) with p = 0.002. This is the same for the overall survival (59% vs. 4 2%, p = 0.002). Tumors with an extension to the mobile tongue or the b ase have a poor prognosis (p < 0.002). The radiobiological factors sho w less recurrences if the total duration of the treatment is < 55 days , the number of days between External Beam Irradiation and brachythera py is < 20. The security margin seems important also. Conclusions: For the combination external irradiation and brachytherapy, the multivari ate study for local control shows that ony T, localization, and the to tal duration of treatment are significant. For complications, classifi ed into four grades, only the dose rate is significant.