Risk stratification for splenic marginal zone lymphoma based on hemoglobin, platelet count, high LDH level and extrahilar lymphadenopathy: development and validation on 593 cases

We report an international retrospective study of 593 Splenic Marginal Zone Lymphoma (SMZL) patients aiming to identify factors conditioning the starting of treatment and the factors influencing lymphoma-specific survival (LSS). Logistic regression was used to identify the factors associated with treatment. A Cox regression was used to analyze LSS in a training set of 366 patients. This produced a prognostic index (PI) and enabled to identify three risk groups. The resulting stratification was validated in another set of 227 patients. The present stratification was compared with the Interguppo Italiano Linfomi (IIL) score in the set of 450 patients for whom all the required data were available using an extension of the net reclassification improvement. Hemoglobin, extrahilar lymphadenopathy and HCV status were associated with the initiation of treatment. Hemoglobin, platelet count, high LDH and extrahilar lymphadenopathy were independently associated with LSS. Three risk groups with significantly different five-year LSS (94%, 78% and 69%, respectively) were identified. This stratification (named HPLL on the basis of determinant factors) had a better discriminative power than the IIL score. This system is useful to stratify SMZL patients into risk groups and may help selecting risk-tailored treatment approaches