A revised international prognostic score system for Waldenstrom's macroglobulinemia

A staging system was developed a decade ago for patients with Waldenstrom's macroglobulinemia (WM), however, since then WM treatments have changed. A revised staging system could better capture prognosis of WM patients in the chemoimmunotherapy era. We developed a revised system based on data from 492 symptomatic patients with at least 3 years and a median of 7 years of follow up while an independent validation cohort included 229 symptomatic patients. We identified age (<= 65 vs 66-75 vs >= 76 years), b2-microglobulin >= 4 mg/L, serum albumin <3.5 gr/dl, and LDH >= 250 IU/L (ULN < 225) to stratify patients in five different prognostic groups and identify a very-low risk as well as a very-high risk group with a 3-year WM-related death rate of 0, 10, 14, 38, and 48% (p < 0.001) and 10-year survival rate of 84, 59, 37, 19, and 9% (p < 0.001). We evaluated this staging system separately in patients >65 years and <65 years, according to the reason for initiation of treatment, among patients receiving frontline rituximab or in patients treated primarily without rituximab. With further validation before clinical use, this revised IPSSWM could improve WM patient risk stratification, is easily available and may be used in the everyday practice to provide prognostic information.