Leukemic transformation of polycythemia vera: A single center study of 23 patients

BACKGROUND. Acute leukemia (AL) may occur as rare and late event of polycythemia vera (PV). METHODS. The current study included 23 patients who developed acute leukemia in a cohort of 414 consecutive PV patients with long-term observation (3208 person years of follow-up), Kaplan-Meier Product-Limit method was used to estimate the cumulative probability of survival; Gehan-Wilcoxon test was applied to compare survival in different groups of patients. RESULTS. Median age was 68 years, and 18 patients (78%) were > 60 years of age. At diagnosis of AL, most patients had a white blood count > 10 × 10 ⁹/L (n = 17; 74%), Hgb <10 g/dL (n = 13; 57%), and platelet count > 50 × 10 ⁹/L (n = 17; 74%). Of 14 patients in whom cytogenetic analysis was available at leukemia transformation, 12 showed high-risk abnormalities including complex karyotype (n = 10), del (7)(q22) sole (n = 1) and del (X)(q26) sole (n = 1), whereas 2 had a normal karyotype. In patients whose karyotype was available at diagnosis of PV, cytogenetic evolution was documented at progression to AL. Treatment consisted of supportive care and/or low-dose chemotherapy (n = 15), or induction chemotherapy (n = 8). This included idarubicin plus cytarabine (n = 3), high-dose cytarabine (n = 4), and fludarabine-based regimen (n = 1). Allogenic stem cell transplantation was offered to a single patient, who is alive at Day + 70. The outcome of patients was poor, with a median survival of 2.9 months (range, 0.6-20.1 mos), with no significant differences between palliation and intensive treatments. CONCLUSIONS. AL following PV has distinct clinical and biologic features. Outcome of patients is poor irrespective of the treatment employed.