Serum beta-2 microglobulin levels are a significant prognostic factor in Philadelphia chromosome-positive chronic myelogenous leukemia

Our objective was to investigate the prognostic significance of serum beta- 2 microglobulin (B2M) levels among patients with chronic myelogenous leukem ia (CML), All patients with Philadelphia chromosome-positive early chronic phase CML (i.e., within 1 year of diagnosis) treated with IFN alpha-based therapy at the M. D. Anderson Cancer Center between 1980 and 1997, in whom pretreatmen t B2M levels were available, were investigated. Two hundred one patients were evaluable. Their median B2M was 2.2 mg/dl (ra nge, 1.1-20 mg/dl), Serum B2M levels were associated with other variables o f prognostic significance, including age, spleen size, WBC count, percentag e of peripheral and marrow blasts, and percentage of marrow basophils, Pati ents with B2M levels >2.9 mg/dl (i.e., the upper quartile of the distributi on) had a significantly lower rate of major cytogenetic response compared t o those in the lower three quartiles (20 versus 52%; P < 0.01), They also h ad a shorter survival, with a 5-year survival rate of 48%, compared with 75 % for those in the lower quartiles (P = 0.01), High B2M levels (>2.9 mg/dl) could identify a group of patients with an adverse outcome within patients in stage I disease (P = 0.02), Results for patients in stages 2-4 were inc onclusive because of the small number of patients in these groups. We conclude that serum B2M levels are an important, and probably independen t, prognostic factor for patients with CML in early chronic phase treated w ith IFN-based therapy.