Adjuvant Radiotherapy for Major Salivary Gland Malignancies: Impact on Locoregional Control and Survival Outcomes

Background/Aim: This study aimed to assess the effect of adjuvant radiotherapy on locoregional control, disease-free survival, and overall survival rates in patients with major salivary gland malignancies. The study also aimed to provide findings to guide clinicians in selecting appropriate candidates for adjuvant radiotherapy and optimizing treatment strategies for this challenging disease. Patients and Methods: A retrospective single-center analysis was conducted, reviewing the medical records of patients diagnosed with major salivary gland malignancies between November 2008 and May 2023. Inclusion criteria were histologically confirmed malignancy, surgical resection of the primary tumor, adjuvant radiotherapy, and availability of clinical and follow-up data. Survival analyses were performed using the Kaplan-Meier method, and Cox proportional hazards regression models were used to assess survival outcomes. Results: The study included 37 patients with major salivary gland malignancies. The most common site was the parotid gland, and the predominant histopathological diagnosis was salivary duct carcinoma. Adjuvant radiotherapy was generally well-tolerated, with the most common acute toxicities being grade 1-2 mucositis and dermatitis. The 5-year overall survival and progression-free survival rates were 93.8% and 62.9%, respectively. Locoregional control rate at five years was 89.1%. Recurrence occurred in 12 patients, with most cases observed within two years from the start of adjuvant radiotherapy. Distant metastasis was observed in nine patients. Conclusion: This retrospective analysis highlights the positive impact of adjuvant radiotherapy on locoregional control and survival outcomes in major salivary gland malignancies. The findings contribute to the existing body of evidence, aiding clinicians in treatment decision-making and potentially informing future prospective studies and treatment guidelines for this challenging disease.