Place of iridium 192 implantation in definitive irradiation of faucial arch squamous cell carcinomas

Abstract

Purpose : We have reviewed the results of 165 T1 and T2 squamous cell carcinomas of the faucial arch treated by definitive irradiation including or not Iridium 192 brachytherapy to ascertain whether a significant relationship existed between Iridium implantation, local control, complications, and survival. Methods and Materials: From March 1971 to November 1990, 58 T1 and 107 T2 (NO: 107 165 ; N1: 30 165 ; N2: 9 165 ; N3: 19 165 ) biopsy proven squamous cell carcinomas of the tonsillar region ( 104 165 ) and the soft palate and uvula ( 61 165 ) were treated in Henri Mondor Hospital by definitive irradiation with curative intent. From 1971 to 1981 (period 1), only guide gutter technique was available, so that implants were reserved for small tumors: patients were either managed by definitive telecobaltherapy to tumor site and neck node areas (Group 1; n = 48; mean dose: 70 Gy; confidence interval: ±5.5; 5 fractions of 1.8 Gy per week) or by exclusive Iridium implant (Group 2; n = 11; all T1 NO; 64 Gy ± 4.8) or by a combination of external beam radiation therapy to tumor site and neck nodes areas and Iridium implant (Group 3; n = 40). In 1981 (Period 2), a new plastic tube technique, which enables implantation of larger areas, was introduced in the department and all patients (Group 4; n = 66) were then managed by external radiation therapy (Group 3 + 4 : 47 Gy ± 4.3) followed by an Iridium implant (31 Gy ± 10.5). Clinically positive neck nodes either received additional external dose with electrons or were excised. Results : Overall 5-year survival (Kaplan Meier) was 21%, 50.5%, and 60% in groups 1, 2, and 3 + 4, respectively ( p < 0.001, log rank). Five-year local control was 58%, 100%, and 91%, respectively ( p < 0.001). Five-year necrosis rate was 4.5%, 20.5% and 18%, respectively (N.S.). Comparison of results between the two periods of the study (Group 1 + 2 + 3 vs. group 4) show that these two groups are statistically comparable according to site and size of tumor and N status and that both local control (77% vs. 94% at 5 years; p < 0.01) and disease-free survival (56% vs. 71%; p = 0.03) were improved after 1980, while there was a trend to an increase in overall survival (42% vs. 53% at 5 years; p = 0.08); nodal control (86% vs. 95% at 5 years), and necrosis rate (11% vs. 20% at 5 years) were not modified. Multivariate analysis showed that both local control ( p < 0.0001) and overall survival ( p < 0.0001) were improved when tumor was implanted. Conclusion : We recommend then to treat T1 and T2 squamous cell carcinomas of the faucial arch by external radiation therapy to tumor site and neck areas (45 Gy/25 fractions/5 weeks) followed by a 30 Gy Iridium implant and, for patients with clinically positive nodes, either a further 25–30 Gy electron beam irradiation to the nodes or neck node dissection.