Prognostic significance of serum beta-2 microglobulin in myelodisplastic syndromes

We investigated the prognostic significance of serum beta-2 microglobulin (b2M) levels among patients with myelodysplastic syndromes (MDS). The population of this study consisted of 380 patients with a diagnosis of MDS referred to our institution between January 1994 and December 1998. Diagnosis was confirmed according to FAB criteria. Pretreatment serum b2M levels were routinely measured in all patients. 29 patients were excluded from the analysis because of serum creatinine levels greater than 1.5 mg/dL. Therefore, 351 patients could be evaluated. According to FAB diagnostic criteria, patients were distributed as follow: 66 RA (19%), 26 (7%) RARS, 98 (28%) RAEB, 104 (30%) RAEB-t, and 57 (16%) CMML. 173 patients have died. Median survival for all patients was 12.6 months. The 178 alive patients were followed for a median time of 6 months (range 0 to 61 months). Median level of serum b2M was 2.6 mg/dL (range 0.8 - 12) in the whole study group, whereas in each FAB category it was as follows: RA 2.3 mg/dL, RARS 2.5 mg/dL, RAEB 2.4 mg/dL, RAEB-t 2.5 mg/dL, CMML 3.5 mg/dL. Correlation analysis revealed that serum b2M levels were associated with age, percentage of circulating blasts, and LDH, whereas no association was found with bone marrow blasts percentage, hemoglobin levels, platelets and abnormal cytogenetics. Levels of b2M greater than 2.0 mg/dL were associated with shorter survival (median 12 vs 23 months - P < 0.01) in the whole study group. However, when the analysis was performed within each FAB category, we were able to document significant association of serum b2M with survival length only in RA and RAEB-t (P < 0.01). In conclusion, serum b2M levels could be useful to identify subgroup with different outcome within subsets of patients stratified by prognostic classification systems, i.e. International Prognostic Scoring System (IPSS). The detailed analysis will be presented.