[Value of the combination of external radiotherapy and curietherapy in carcinoma of the velo-tonsillar region. Statistical study of a series of 361 patients].

From 1977 to 1991, we treated 361 carcinomas of the velotonsillar region, either by brachytherapy alone (18 cases), or by an association of external radiotherapy and brachytherapy (343 patients). The latter was performed using a special technique with iridium wires in plastic tubes with afterloading. The primary was the tonsil in 128 patients, the soft palate in 134 patients. We numbered also 9 posterior pillars, 63 anterior pillars and 27 velotonsillar sulcus. According to the UICC staging system (28), we classified the patients in 90 T1, 141 T2, 119 T3, 2 T4, 9 Tx with 230 N0, 93 N1, 9 N2, 20 N3 and 9 Nx. The results at 5 and 10 years show respectively: local control (LC) 80% and 75%, locoregional control 75% and 70%, global survival 53% and 28%, specific survival 63% and 52%. The univariate study shows at 5 years a better local control for T1-T2 (87%) than for T3 (67%) with p = 0.00004. The locoregional control is better for N0 (80%) than for N+ (66%) with p = 0.002, this is the same for global survival (59% versus 42%, p = 0.002). The two groups were individualised according to the primary. Inside each of these groups, the prognosis is identical for different localisations, which allows to put them together. We can therefore distinguish a group A which includes the tonsil, the soft palate and posterior pillar. This group has a better prognosis (controls and survivals) than group B (anterior pillar and velotonsillar sulcus) (p < 0.002). The tumours extended to the mobile tongue, the base of the tongue or the velotonsillar sulcus have a poorer prognosis than those without propagation or with an upwards propagation (p < 0.002). The statistical study of radiobiological factors that can influence the tissular repair shows that there are less recurrences if the duration of treatment is inferior to 55 days and if the interval between external irradiation and brachytherapy is inferior to 20 days. A sufficient safety margin seems also necessary for a good local control. The dose rate within the limits used does not seem to influence the local control and the total dose delivered to the tumour, but this is not surprising since the highest doses are given to the tumours with the smallest regression during external irradiation. The multivariate study for local control shows that the most significant factors are the T, the tumoral localisation and the total duration of treatment. For complications (classified in 4 stages), the dose rate is the most significant factor.