Red Blood Cell Transfusion Requirement at Diagnosis Adversely Affects Both Overall and Leukemia-Free Survival in Primary Myelofibrosis - Increased Serum Ferritin or Total Transfusion Burden Does Not

BACKGROUND: In myelodysplastic syndromes (MDS) without excess blasts, red blood cell (RBC) transfusion requirement has been associated with poorer overall (OS) and leukemia-free (LFS) survival, suggesting that transfusion dependency is a marker of more severe disease (

METHODS: We reviewed medical records to ascertain the clinical and laboratory features of 185 consecutive patients diagnosed with PMF according to the 2001 World Health Organization (WHO) criteria. Patients were excluded if ferritin measurements at time of diagnosis were unavailable. OS and LFS curves were constructed by Kaplan-Meier method, taking the interval from the date of diagnosis to death, leukemic transformation, or last contact. Log-rank test was used to test the homogeneity of survival curves over different groups. Cox proportional hazards model was utilized to determine the impact of various clinical and laboratory variables on OS and LFS.

RESULTS:

• Clinical characteristics at diagnosis: Median age was 58 years (range 15–81; 110 males). Median serum ferritin level at diagnosis was 164 ng/mL (range 1–3903) and was ≥1000 ng/mL in 22 patients (12%). 101 (55%), 65 (35%) and 19 (10%) patients were assigned low, intermediate- and high-risk disease category (

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  ). In addition, 32 (17%) patients required RBC transfusions, 33% had constitutional symptoms and 39% displayed ≥ 1% circulating blasts. Where evaluated, 40% of the patients had cytogenetic abnormalities and 56% JAK2V617F.

• Events during the disease course: At a median follow-up of 28 months (range 0.5–231), 79 (43%) deaths and 15 (8%) leukemic transformations were documented. During this period, 126 (68%) patients required some form of therapy other than transfusion, including splenectomy in 33 (18%); only 4 underwent allogeneic stem cell transplantation. Causes of death were documented in 33 instances and none were attributed to iron overload. Median peak serum ferritin level during the disease course was 231ng/mL (range 9–13,080); 144 (78%) patients had peak levels <1000 ng/mL, 28 (15%) between 1000 and 3000 ng/mL, and 13 (7%) above 3000 ng/mL. Number of total RBC transfusions ranged from none to 121. Iron chelation therapy was reported in 62 patients (34%).

• Prognostic factors for OS and LFS: Kaplan-Meier projected median survival was 72 months. By univariate analysis, increased serum ferritin level at diagnosis considered as either a continuous (p<0.0001) or categorical (≥ 1000 ng/mL) variable (p<0.0001), RBC transfusion requirement at diagnosis (p<0.0001) and higher number of total RBC units transfused during the course of the disease (p=0.004) were all associated with inferior survival.

However, only RBC transfusion requirement at diagnosis sustained its prognostic significance when age and conventional prognostic risk scores were added to the multivariable model as covariates. Similarly, a peak serum ferritin level of > 3000 ng/mL documented during the disease course was not detrimental to survival. History of iron chelation therapy was associated with shortened survival (p=0.003). Multivariable analysis that included previously described risk factors for LFS also identified RBC transfusion requirement at diagnosis as an additional and independent risk factor.

CONCLUSIONS: Serum ferritin level at time of diagnosis or during the disease course of PMF lacks independent prognostic value for either OS or LFS. The same is true for total transfusion burden. However, although hemoglobin <10 g/dL is a component of all currently utilized prognostic scoring systems for PMF, the presence of a more severe erythropoietic defect as indicated by RBC transfusion need at time of diagnosis has an additional adverse prognostic value for both OS and LFS.