Background: Postpolycythemic (PV) and postthrombocythemic (ET) myeloid metaplasia are consensually referred to as secondary myelofibrosis (sMF). Prognostic variables in sMF are not as well defined as they are for de novo myelofibrosis with myeloid metaplasia (MMM), which is also known as agnogenic myeloid metaplasia (AMM). Such information is particularly crucial for management decisions in transplant-eligible patients.
Methods: Diagnoses of PV and ET required fulfillment of the World Health Organization criteria for the diagnosis of MMM as well as an antecedent history of either polycythemia vera or essential thrombocythemia that was supported by bone marrow examination. Cytogenetic findings were classified as being either favorable (normal or isolated 13q- or 20q- clones) or unfavorable (presence of abnormalities other than 13q- and 20q-).
Results: The study population was comprised of 66 young patients (age <60 yrs) with sMF, including 37 patients with PV and 29 patients with ET. Multivariate analysis of parameters other than cytogenetics identified older age (P = .02), anemia (hemoglobin level <10 g/dL [P = .007]), and PV (P = .009) to be independent risk factors for shortened survival. However, when such analysis was restricted to patients in whom cytogenetic studies were performed (n = 31 patients), the presence of unfavorable cytogenetic abnormalities (i.e., clones other than 20q- and 13q-) became the only adverse prognostic factor for survival (P = .001). A similar analysis in a temporal cohort of 50 age-matched patients with AMM also identified unfavorable cytogenetics as an independent predictor of poor survival, along with thrombocytopenia and anemia.
Conclusions: The results of the current study suggest that cytogenetic findings might supersede AMM-derived prognostic scoring systems for predicting survival in patients with sMF.