Early Clinical Outcomes of Definitive Volumetric Modulated Arc Therapy in Locally Advanced Oral Cavity Cancers: A Prospective, Single-Center Study

Background Evidence from prospective evaluations of outcomes in locally advanced, surgically unresectable oral cavity squamous cell carcinoma (OCSCC) treated with definitive chemoradiotherapy is limited. Methodology We conducted a single-center, prospective, observational study to evaluate early tumor response, acute toxicities, treatment compliance, and survival outcomes in patients with unresectable, locally advanced OCSCC treated with volumetric modulated arc therapy (VMAT) with concurrent three-weekly cisplatin in feasible patients. Results A total of 55 consecutive patients (median age = 56 years; Eastern Cooperative Oncology Group performance status = 0-2) were included. Overall, 40 (72.7%) patients received concurrent cisplatin-based chemoradiotherapy, and 15 (27.3%) underwent VMAT alone. At three months post-treatment, the objective response rate for the entire cohort was 78.2% (95% confidence interval (CI) = 65.0-88.2%), and the disease control rate was 90.9% (95% CI = 80.0-97.0%). Severe (grade ≥3) mucositis occurred in approximately half of the patients, whereas other acute and hematologic toxicities were generally ≤25%. The median overall treatment time was 43 days. With a median follow-up of 13.4 months, the median progression-free survival (PFS) and overall survival (OS) were 16.7 (95% CI = 14.9-18.5), and 18.6 months (95% CI = 16.0-21.2), respectively, with one-year PFS and OS rates of 78% (95% CI = 67-89) and 80% (95% CI = 69-91), respectively. Conclusions In patients with unresectable, locally advanced OCSCC with good performance status, definitive chemoradiotherapy delivered with VMAT is feasible and effective, achieving reasonable response rates and acceptable acute toxicities; however, longer follow-up is required to fully assess late toxicities.