clearly established as a prognostic factor in patients with MBL, whether or not it can be used to identify those individuals with a circulating B-cell clone whose OS is shorter than unaffected individuals in the general population has not yet been determined. Third, while the diagnosis of CLL and MBL should be based in part on clinical outcomes, yet to be discovered biologic characteristics could be an equally important consideration. The 5% prevalence of MBL in the general population over age 60 coupled with the markedly lower prevalence of CLL is consistent with the multi-hit hypothesis of human malignancy and suggests additional biologic events must occur for MBL to progress to CLL. Identification of the biologic events that related to progression could lead to incorporation of these characteristics in the classification system as well as the development of early intervention strategies.
