Clinicopathologic features and outcome of Chinese patients with myelofibrosis

Abstract

INTRODUCTION: Myelofibrosis (MF) is a myeloproliferative neoplasm (MPN) comprising primary myelofibrosis (PMF) and myelofibrosis developing from either polycythemia vera (post-PV MF) or essential thrombocythemia (post-ET MF). METHODS: Two hundred and sixty-seven consecutive patients with MF (PMF, N=206); post-PV MF, N=26; post-ET MF, N=35) diagnosed between January 1988 and December 2013 at seven regional hospitals in Hong Kong were prospectively followed up. Data on the clinicopathologic features and treatment outcome were collected. RESULTS: The median duration of follow-up was 45 (1 – 247) months. The median overall survival (OS) was 65 months (95% confidence interval, CI: 56.3–73.7). The 5-year and 10-year OS were 52.2% and 26.7% respectively. On univariate analysis, factors associated with an inferior OS included age > 65 years (hazard ratio ,HR, =1.81; 95% CI:1.33–2.48; P<0.001), the presence of constitutional symptoms (HR=1.52; 95% CI:1.11–2.08; P=0.009), hemoglobin < 10 g/dL (HR=1.71; 95% CI:1.25–2.35; P=0.001), circulating blasts ≥ 1% (HR=1.55; 95% CI:1.13–2.16; P=0.007), platelet < 100 x 109/L (HR=2.51; 95% CI:1.79–3.53; P<0.001), high risk IPSS (HR=3.09; 95% CI: 1.78–5.37; P<0.001), intermediate-2 risk DIPSS (HR=2.37; 95% CI: 1.38–4.06; P=0.002), high risk DIPSS (HR=2.92; 95% CI:1.51–5.64; P=0.001), transfusion dependence within the first year of diagnosis (HR=2.61; 95% CI:1.92–3.55; P<0.001), transfusion dependence after the first year of diagnosis (HR=2.42; 95% CI:1.61–3.54; P<0.001), palpable hepatomegaly at diagnosis (HR=1.44; 95% CI:1.06–1.96; P=0.02) and secondary AML (HR=1.75; 95% CI:1.24–2.47; P=0.001). On multivariate analysis, post-PV MF (P=0.03), platelet < 100 × 109/L (P=0.001), high risk IPSS (P=0.009), transfusion dependence within the first year (P=0.001), transfusion dependence after the first year (P=0.02), and transformation to secondary acute myeloid leukemia (AML) (P=0.007) were independent risks associated with inferior OS. On univariate analysis, factors associated with increased risk of secondary AML include age ≤ 55 years (odds ratio [OR] = 2.61; 95% CI:1.33–5.12; P=0.005), circulating blasts ≥ 1% (OR=2.24; 95% CI:1.18–4.26; P=0.01), transfusion dependence within the first year (OR=5.57; 95%:2.16–14.88; P<0.001), transfusion dependence after the first year (OR=5.57; 95% CI:2.16–14.88; P<0.001), hepatomegaly (OR=4.05; 95% CI:2.03–8.10), splenomegaly (OR=3.71; 95% CI:1.09–9.26; P=0.04), abnormal karyotypes (OR=3.3; 95% CI:1.14–9.56; P=0.02), and the presence of unfavourable karyotypes (OR=4.9; 95% CI: 1.22–19.96). On multivariate analysis, transfusion dependence within the first year of diagnosis (P=0.04), transfusion dependence after the first year of diagnosis (P=0.003) and hepatomegaly (P=0.006) were independent risks associated with secondary AML. The 5-year and 10-year risks of leukemic transformation were 17.1% and 29.7 respectively. Factors associated with inferior leukemia-free survival (LFS) on univariate analysis included post-ET MF (HR=2.15; 95% CI: 1.03–4.50; P=0.04), presence of constitutional symptoms (HR=1.85; 95% CI:1.04–3.31; P=0.04), circulating blasts ≥ 1% (HR=2.89; 95% CI:1.62–5.16; P<0.001), platelet count < 100 x 109/L (HR=2.56; 95% CI: 1.35–4.84; P=0.004), transfusion dependence within the first year of diagnosis (HR=3.05; 95% CI: 1.70–5.50; P<0.001), transfusion dependence after the first year of diagnosis (HR=6.49; 95% CI: 2.33–18.10; P<0.001), hepatomegaly (HR=3.21; 95% CI:1.69–6.08; P<0.001) and unfavorable karyotype (HR=3.01; 95% CI:1.08–8.35; P=0.03). On multivariate analysis, male gender (P=0.05), presence of constitutional symptoms (P=0.04) and unfavorable karyotypes (P=0.01) were independent risks associated with inferior LFS. Eighteen patients underwent allogeneic haematopoietic stem cell transplantation (HSCT) (matched sibling, N=14; matched-unrelated, N=4), with 15 patients achieving complete remission. Seven patients relapsed with subsequent progression to secondary AML. Acute and chronic graft-versus-host disease occurred in seven (39.9%) and six (33.3%) patients respectively. Transplant-related mortality occurred in three patients. The 5-year and 10-year OS following HSCT was 51.5%. CONCLUSION: Findings of this study complement current prognostic models in guiding treatment decisions at diagnosis and during the course of MF. © 2014 by The American Society of Hematology