Purpose: Our aim was to study the different factors that influence the results and complications in a series of 448 carcinomas of the oral tongue treated from January 31, 1972 to December 31, 1986, by brachytherapy (Br) +/- neck dissection (181 cases) or combination of external beam irradiation and brachytherapy (EBI + Br) (267 cases).
Methods and materials: The patients distribution (TNM classification 1979) was: 125 T1, 186 T2, 128 T3, 9 T4Tx, 78% N0, and 22% N+. We used guide gutter or plastic tubes technique (Paris system dosimetry). Results at 5 and 10 years are: local control 68% and 64%, locoregional control 58% and 53%, specific survival 45% and 39%, and overall survival 44% and 27%.
Results: In the univariate analysis for local control (LC) and overall survival (OS), we considered the tumoral factors. At 5 years, the LC for T1, T2, T3 are 93%, 65%, and 49%, and the OS 69%, 41%, and 25%, respectively (p < 0.002). The lesions of the undersurface of the tongue have a better LC (77%) than other localizations (64%) (p = 0.02). For general factors, the index of general health condition, age, and sex were not significant for LC, but proved significant for OS (p = 0.01). Significant radiobiological factors: the safety margin (expressed by the ratio treated surface on tumoral surface > or = 1.2) is significant for LC and OS. This is the same if the interval between EBI and Br is < or = 20 days. Neither the dose rate, the spacing between the sources, the total dose, nor Br dose were significant, but the last two were adapted according to the infiltration. In the univariate study for grade 2 and 3 complications (tissue and bone), the surface treated (> 12 cm2), and the dose rate > 0.7 Gy/h were significant.
Conclusion: The multivariate study showed that the small size of the lesion is the most important factor for local control, with brachytherapy alone for T1T2N0 and the number of days between EBI and brachytherapy < or = 20 days. For the complications, the most important factors are the total dose > 80 Gy and a treated surface > 12 cm2.