Clinicopathological characteristics and prognostic factors for primary thyroid lymphoma: report on 28 Chinese patients and results of a population-based study

OBJECTIVES: Few studies on prognostic indicators for primary thyroid lymphoma (PTL) have been presented due to the uncommon nature of the tumor. This is the first study to explore the independent prognostic factors in the 2 PTL subtypes. METHODS: We retrospectively reviewed 1,653 cases of PTL. The cases comprised 28 Chinese patients from a local cohort and 1,625 patients from the Surveillance, Epidemiology, and End Results database from 1973 to 2013. Statistical analysis was performed to determine the demographics and prognostic factors of PTL patients. RESULTS: The disease-specific survival (DSS) and prognostic indicators were significantly different between patients with extranodal marginal zone B-cell lymphoma of the mucosa-associated lymphoid tissue (MALT) and patients with diffuse large B-cell lymphoma (DLBCL). Patients with MALT lymphoma were younger (P=0.011) and had lower clinical stage (P=0.014) compared to patients with DLBCL. Cox regression analysis revealed that age, treatment modalities employed, clinical stage, and number of other types of cancer were independent prognostic factors for DLBCL patients. CONCLUSION: PTL demonstrates specific clinical features and is associated with a relatively good prognosis. Older age is associated with poor DSS in both MALT patients and DLBCL patients. Additionally, combination of different treatment modalities is associated with improved DSS in DLBCL patients.