Treatment facility volume and patient outcomes in Waldenstrom macroglobulinemia.

Waldenstrom macroglobulinemia (WM) has an annual incidence of 3-3.2 cases per million-person/year. National Cancer Data Base was used to identify newly diagnosed WM cases requiring initiation of therapy and their annual facility volume was used to divide the treatment facilities into four quartiles (Qs). Cox regression was used to analyze the association between facility volume and survival, adjusted by demographics, socioeconomic, geographic, comorbidity factors and year of diagnosis. A total of 3064 patients treated in 795 facilities were included. The unadjusted median overall survival (OS) by facility volume was: Q1:6.5 years (5-year OS 55%), Q2:7 years (5-year OS 60%), Q3:8 years (5-year OS 64%), and Q4: NR (5-year OS 71%), p < 0.0001. Our results demonstrated that a volume-outcome relationship exists in WM and is an independent predictor of overall survival in addition to the established risk factors as age and disease severity.