The role of postoperative radiotherapy (PORT) in lymphoepithelial carcinoma of the salivary gland (LECSG) and the effect of postoperative EBV DNA on prognosis.

Abstract

Whether postoperative radiotherapy (PORT) could improve survival and the role of EBV DNA remains unclear for patients with lymphoepithelial carcinoma of the salivary glands (LECSG). 360 patients were included. Independent prognostic factors were selected using a Cox proportional hazards model and incorporated into risk stratification. The number of positive lymph nodes (PLNs) ≥ 3 and tumor size ≥ 3 cm were independent factors for PFS in patients with neck dissection (ND). Patients were divided into three groups: high-risk, size ≥ 3 cm&PLNs ≥ 3; intermediate-risk, size < 3 cm&PLNs ≥ 3 or size ≥ 3 cm&PLNs < 3; low-risk, size < 3 cm&PLNs < 3. The 5-year PFS rate of the low-, intermediate- and high-risk patients receiving non-PORT and PORT was 87.9% vs 93.5% (p = 0.12), 41.2% vs 81.1% (p < 0.001), 18.0% vs 51.1% (p = 0.034). N stage was an independent factor for PFS in patients with non-neck dissection (NND) and patients were divided into two groups: low-risk, N0; and high-risk, N1/2. The 5-year PFS rate of the low-risk, and high-risk patients receiving non-PORT and PORT was 77.9% vs 94.3% (p = 0.0019), 21.4% vs 71.3% (p = 0.015). Compared with EBV DNA = 0, the 5-year PFS rate of patients with EBV DNA > 0 was 19.9% vs 91.3% (p < 0.001). In patients with EBV DNA = 0, the 5-year PFS rate of patients with or without PORT was 95.1% vs 92.3% (p = 0.082); while in patients with EBV DNA > 0, the 5-year PFS rate was 37% vs 9.2% (p = 0.0056). In patients with ND, PLNs < 3&size < 3 cm patients did not benefit from PORT. Detectable EBV DNA after surgery was a negative prognostic factor.