Splenic marginal zone lymphoma: A US population-based survival analysis (1999-2016).

Background: Splenic marginal zone lymphoma (SMZL) is a rare tumor without a uniform treatment approach. The authors describe a large population-based study evaluating survival outcomes of patients with SMZL according to the treatment received.

Methods: From the Surveillance, Epidemiology, and End Results database, patients were selected who had SMZL diagnosed from 1999 to 2016. Observation, splenectomy, chemotherapy, and splenectomy with chemotherapy were the evaluated treatment strategies. Cox and Fine and Gray regression models were used to evaluate overall and SMZL-specific survival, respectively.

Results: In total, 1671 patients were selected for the analysis. Most patients were aged >60 years (71.3%), White (89.7%), and non-Hispanic (91.7%). Transformation to diffuse large B-cell lymphoma (DLBCL) occurred in 71 patients (4.2%), and the 10-year transformation rate was 8.6% (95% CI, 6.6%-10.9%). In multivariable analysis, shorter SMZL-specific survival was associated with age ≥60 years (subdistribution hazard ratio [SHR], 1.85; 95% CI, 1.40-2.45; P < .001), Hispanic ethnicity (SHR, 1.50; 95% CI, 1.06-2.13; P = .023), DLBCL transformation (SHR, 2.10; 95% CI, 1.48-2.97; P < .001), and the presence of B-symptoms (SHR, 1.67; 95% CI, 1.23-2.27; P < .001). Compared with splenectomy, observation (SHR, 0.92; 95% CI, 0.67-1.28; P = .636), chemotherapy only (SHR, 1.28; 95% CI, 0.93-1.76; P = .127), and splenectomy plus chemotherapy (SHR, 1.43; 95% CI, 0.96-2.13; P = .089) showed no significant differences in SMZL-specific survival. Predictors of shorter overall survival were age ≥60 years (hazard ratio, 2.98; 95% CI, 2.37-3.76; P < .001) and the presence of B-symptoms (hazard ratio, 1.33; 95% CI, 1.06-1.67; P = .014).

Conclusions: There were no significant differences in overall or SMZL-specific survival by treatment strategy. Older age, Hispanic ethnicity, DLBCL transformation, and B-symptoms were associated with a worse prognosis.