Efficacy of Surgery in Patients with Stage I Primary Parotid Gland Lymphoma: A Population-Based Study.

Background: Limited and controversial evidence is available on the efficacy of surgery for patients with stage I primary parotid gland lymphoma. Thus, we aimed to investigate whether surgery can enhance the prognosis of patients with stage I primary parotid gland lymphoma using large sample data.

Methods: From 1998 to 2015, we searched the Surveillance, Epidemiology, and End Results (SEER) program database and extracted information regarding patients with stage I primary parotid gland lymphoma; we classified these patients into surgery and nonsurgery groups. We calculated overall survival (OS) and cancer-specific survival (CSS) using Kaplan-Meier curves and log-rank testing. Propensity score matching (PSM) analysis was also used to further account for confounding variables before comparing the OS and CSS again. We used the COX proportional hazard regression model in both multivariate and univariate analyses.

Results: We enrolled 918 patients with stage I primary parotid gland lymphoma, among which 656 (71.5%) patients underwent surgery. Before PSM, the surgery group had better OS (hazard ratio (HR) = 0.673, 95% confidence interval (CI): 0.519-0.873, and =0.003) and CSS (HR = 0.595, 95% CI: 0.403-0.879, and =0.008) than the nonsurgery group. After PSM, surgery was still a beneficial factor for OS (HR = 0.569, 95% CI: 0.399-0.810, and =0.002) and CSS (HR = 0.384, 95% CI: 0.220-0.669, and =0.001). Furthermore, in univariate and multivariate analyses, total parotidectomy significantly increased OS (=0.001 and =0.021, respectively) and CSS (=0.001 and =0.037, respectively).

Conclusions: In summary, the prognosis of patients with stage I primary parotid gland lymphoma can be significantly improved by surgery. Moreover, total parotidectomy was a protective factor for OS and CSS before and after PSM analysis, suggesting that surgery acts as a significant component in multimodal therapy for early primary parotid gland lymphoma.