Long-term survival in Waldenstrom macroglobulinemia: 10-year follow-up of Southwest Oncology Group directed intergroup trial S9003

The survival of patients with Walden- strom macroglobulinemia (WM) varies enormously. The development of prognos- tic models in WM has been fraught by limited follow-up in current studies. Here, we update the outcome of a prospective WM trial with a median follow-up of 10 years for live patients. Of the 59 previ- ously untreated patients who initially were observed, only 12 patients (21%) required therapy at a median follow-up of 100 months. Multivariate analysis among the 183 patients requiring therapy reaf- firmed age 70 years or greater, previous nonprotocol therapy, and (S-2 microglobu- lin (B2M) of 3 mg/dL or greater as prog- nostic factors. Importantly, increased se- rum lactate dehydrogenase (LDH) was identified as an additional independent variable, which improved risk assess- ment beyond the recent WM international prognostic scoring system (ISSWM). By using age, previous therapy, B2M, and LDH, we identified 3 risk groups with 8-year survival estimates of 55%, 33%, and 5% (P < .001). These data provide novel insights into factors predicting long- term outcome in WM. This trial has been registered with www.cancer.gov under ID 4852904.