Head and neck squamous cell carcinoma (HNSCC) is one of the most prevalent malignant tumor globally, and over 60% of patients present locoregionally advanced tumors. Platinum-based chemoradiotherapy is a widely adopted treatment for patients with unresectable locoregionally advanced HNSCC, those ineligible for surgery and those refusing surgery due to potential sequelae. While this approach has yielded favorable results in developed countries, its effectiveness in real-world settings in developing countries remains underexplored. Investigating treatment outcomes in this context is essential for optimizing oncologic care.

To assess the toxicity profile, tumor response, event-free survival (EFS), and overall survival (OS) in patients with locoregionally advanced HNSCC treated with definitive platinum-based chemoradiotherapy.

This retrospective study included 233 patients treated at the Oncology Service of the General Hospital of University of Campinas (UNICAMP). Inclusion criteria encompassed patients aged 18 or older, with an Eastern Cooperative Oncology Group (ECOG) of 2 or lower, who underwent radiotherapy (RT) combined with either weekly or every-three-weeks administration of cisplatin (CDDP) or carboplatin (Carbo) as definitive treatment. Grade 3 or 4 adverse events were documented according to the National Cancer Institute, Common Terminology Criteria for Adverse Events (NCI CTCAE v5.0) standards. Response Evaluation Criteria in Solid Tumors (RECIST) criteria. Survival outcomes were estimated with the Kaplan-Meier method, and statistical comparisons were performed using the log-rank test and Cox proportional hazards regression for univariate and multivariate analyses.

The median age of patients enrolled in study was 60 years. Most enrolled subjects were males, active or former smokers and drinkers, had good performance status and comorbidities, and presented moderately differentiated and advanced tumors. Tumors were equally distributed in oral cavity, pharynx and larynx. Half of the patients developed grade 3 or 4 toxicities, with nausea/vomiting and nephrotoxicity being more frequently observed in the RT + CDDP group, while anemia and neutropenia were predominant in the RT + Carbo group. A total of 75% of patients achieved either complete or partial tumor response, with no significant impact from the treatment regimen. The two-year EFS and OS rates were 43.3% and 66.0%, respectively. Poor prognosis was associated with active smoking, ECOG performance status ≥ 2, stage IV disease, and treatment with RT + Carbo. Patients with these characteristics had an approximately twofold higher risk of presenting relapse and disease progression leading to death.

This study highlights RT and CDDP as the most effective definitive treatment for patients with locoregionally advanced HNSCC from a Brazilian public hospital. Nevertheless, further prospective and randomized phase III study conducted with those patients is essential to define the optimal treatment strategy for these patients Acknowledgements: The study was supported by Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES).