Abstract
Introduction: Radiotherapy for head and neck cancer frequently causes acute toxicities that impair treatment continuity and quality of life. However, integrated data on simultaneous occurrence of mucositis, radiodermatitis, and dental disorders in Brazilian public health system (SUS) are scarce. Objective: To evaluate the incidence and severity of adverse events and identify associated clinical and treatment factors. Method: Retrospective cohort study at a single radiotherapy center in SP, Brazil, between January 2021 and December 2024. Multivariate logistic regression was used to identify independent predictors of severe mucositis and radiodermatitis, adjusting for age, radiation dose, and concomitant chemotherapy. Results: Of the 180 patients screened, 146 were analyzed (34 have been excluded, 18 due to incomplete records, 10 due to death or treatment abandonment before fraction 10, and 6 due to transfer). Mucositis occurred in 142 patients (97.3%; grade 3 in 28.8%). Radiodermatitis occurred in 138 patients (94.5%; grade 3 in 13.7%). Dental disorders were documented in all 146 patients (100%), driven by hyposalivation (98.6%), radiation caries (42.5%), and periodontal disease (31.5%). In multivariate analysis, concomitant chemotherapy was an independent predictor of moderate-to-severe mucositis (OR=4.42; 95% CI 2.01–9.71; p<0.001), while total radiation dose ≥60 Gy was independently associated with severe radiodermatitis (OR=3.08; 95% CI 1.28–7.41; p=0.012). Conclusion: The high prevalence and severity of acute toxicities underscore the need for structured multidisciplinary supportive care. The 100% dental disorder rate reflects the vulnerable oral health background of SUS patients. These real‑world data offer actionable evidence for clinical protocols and public health policies.