Purpose: To study the rate and severity of complications in a series of 1134 patients treated by definitive irradiation for tumors of the oral cavity (772 cases) or the oropharynx (361 cases).
Methods and materials: Patients were staged as 29.5% T1, 42% T2, 26% T3, 2.5% T4-Tx, and 74.5% N0 tumors. We treated 364 patients with brachytherapy only (192Ir) for the primary lesion. External irradiation and brachytherapy were combined for 770 patients.
Results: The results included local control and survival. Out of 1134 patients, 330 had 376 complications. Grade 1 complications occurred in 20% of the patients, Grade 2 in 9%; Grade 3 in 4%; and Grade 4 in 0.2%. Of the Grade 1 complications, 78% were soft tissue and only 24% were bone complications. For the more severe grades (2, 3, and 4), there were 56 soft tissue complications and 90 bone complications out of 1340 patients. The statistical analysis included tumor-related factors and treatment-related factors. For the first two factors, only tumor location was significant. The treatment-related factors significant for complications were studied in univariate and multivariate study. This multivariate study confirmed that for soft tissue complications dose rate and volume treated were important (p < 0.001). It also confirmed that for bone complications, total dose > 80 Gy, dose rate > 0.7 Gy/h, and the absence of leaded protection of the mandible were all important factors.
Conclusion: This statistical study should allow future reduction of severe complications (Grades 2, 3, 4), if treatment factors inducing them can be taken into account. This is not always possible for very large tumors.