Radiation therapy for parotid gland tumors: long term data from a large single Institution experience.

Abstract Background parotid gland tumors (PGT) are rare entities. Surgery plays a key role in the treatment of PGT, post-operative radiation therapy (PORT) is necessary in order to reduce the recurrence rates. Histological subtypes (HS) and differentiation grade (DG) are extremely various and so is their clinical behavior. This large retrospective paper aims to identify factors associated with treatment toxicity, loco-regional recurrence and survival in patients with PGT. Methods 152 patients with PGT were treated with surgery and PORT at our Department between 1992 and 2019. Medical records reported patients, disease and treatment characteristics, acute and late toxicities. Loco-regional control (LC), overall survival (OS), cancer specific survival (CSS) and metastases free survival (MFS) were analyzed as outcome endpoints. Results severe (> G2) acute mucositis and dermatitis were 20% and 10% respectively. Severe acute mucositis was reported more frequently in patients treated with > 60 Gy on tumor bed (p = .001) and in patients treated also on the neck (p = .006). The most frequent reported late toxicities were skin fibrosis (any grade) and xerostomia (≤ G2), 67% and 50% respectively. LC, OS, CSS and MFS rates at 10 year were respectively 67, 64, 76, 80 (%). Better Karnofsky Performance Status at diagnosis, more favorable HS, well differentiated PGT, less advanced pathological stage and the absence of nodal disease are related with better survival outcomes. Conclusion our data are in line with current literature: high grade and locally advanced PGT have the worst prognosis. Clinical trials are needed to define better treatment strategies for PGT.