Jawhar M, Schwaab J, Alvarez-Twose I, et al. - In this study with training and a validation set, the goal was to construct a risk score, by combining clinical and mutation features, for patients with advanced systemic mastocytosis (AdvSM). Participants were 383 in total and were grouped as training set including 231 patients with AdvSM from the German Registry on Disorders of Eosinophils and Mast Cells and; as validation set including 152 patients from various centers for mastocytosis in the United States and Europe, all within the European Competence Network on Mastocytosis. Researchers identified risk factors that were related to overall survival (OS) and assigned hazard ratio–weighted points to these factors to define 3 risk categories: low risk (median OS, not reached), intermediate risk (median OS, 3.9 years; 95% CI, 2.1 to 5.7 years), and high risk (median OS, 1.9 years; 95% CI, 1.3 to 2.6 years; P < .001). A median follow-up of 2.2 years (range, 0 to 23 years) revealed a leukemic transformation to secondary mast cell leukemia (32%) or secondary acute myeloid leukemia (68%) in 63 (16%) of 383 patients. Leukemia-free survival was also predicted by the mutation-adjusted risk score (MARS). Overall, experts have offered a validated, five-parameter, WHO-independent prognostic score, named as MARS, which not only defined 3 risk groups among patients with AdvSM but also may improve up-front treatment stratification for these rare hematologic neoplasms.