Purpose: Studies using intensity-modulated radiation therapy (IMRT) in the treatment of head and neck tumors have shown to decrease acute and late radiation toxicity. However, the high conformity of this technique can increase the risk of recurrence due to geographic miss. The aim of this study was to analyze whether the results of IMRT met the theoretical expectations concerning treatment efficacy.
Methods: From a total of 185 patients (152 males and 33 females, mean age 58±10.36 years) 176 were evaluable and were studied. Eighty-nine (48.1%) patients had surgical treatment and 50 of them were scheduled for concomitant cisplatin chemotherapy. Irradiation was performed using IMRT, a sliding window with 9 fields in a Varian 2100 C/D linear accelerator, X-ray beam, 6 MeV. The prescribed dose in the planning treatment volume (PTV1), i.e., the area of the primary tumor and nodal area, was 66 Gy/2.2 Gy-70 Gy/2.12 Gy. In the PTV2 (the area at high risk) the dose was 60Gy/2 Gy-59.4 Gy/ 1.8 Gy, and in the PTV 3 (the area treated with prophylactic irradiation) the prescribed dose was 54 Gy/1.8 Gy/50.4 Gy/1.53 Gy.
Results: The 3-year overall survival (OS) and relapse-free survival (RFS) of IMRT-treated patients, most of whom were in stages III and IV (158 out of 177), were 50 and 57%, respectively. Using postoperative radiotherapy/chemoradiotherapy 3-year locoregioncal control was achieved in 75% of the cases as compared with 35% in non-operated patients.
Conclusions: The worst outcomes were found in oral cavity and hypopharyngeal tumors, and the best in laryngeal and oropharyngeal tumors. Better results were found in surgically treated patients, and in lower disease stages. Despite the high conformity of dose distribution and efforts to spare healthy tissues, most cases of locoregional relapse occurred in areas receiving the full radiation dose. If dividing relapses into cases of persistence and local recurrence, the former predominated.