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

Background: 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).

Patients and methods: 360 patients were included. Independent prognostic factors were selected using a Cox proportional hazards model and incorporated into risk stratification.

Results: 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).

Conclusions: 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.