Risk stratification for Splenic Marginal Zone Lymphoma based on haemoglobin concentration, platelet count, high lactate dehydrogenase level and extrahilar lymphadenopathy: development and validation on 593 cases.

This international retrospective study of 593 Splenic Marginal Zone Lymphoma (SMZL) patients aimed to identify factors that determine treatment initiation and influence lymphoma-specific survival (LSS). Logistic regression was used to identify the factors associated with treatment. A Cox regression was used to analyse LSS in a derivation cohort of 366 patients. This produced a prognostic index (PI) and enabled the identification of three risk groups. The resulting stratification was validated in another cohort of 227 patients and compared with the Interguppo Italiano Linfomi (IIL) score in the group of 450 patients for whom all the required data were available using an extension of the net reclassification improvement. Haemoglobin concentration (Hb), extrahilar lymphadenopathy and hepatitis C virus status were associated with the initiation of treatment. Hb, platelet count, high lactate dehydrogenase level 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 for stratifying SMZL patients into risk groups and may help in the selection of risk-tailored treatment approaches.