Another important question is whether all CLL cases are preceded by MBL, or if some (e.g. biologically aggressive) CLL cases develop de novo. This is of importance because if MBL consistently precedes CLL researchers could develop prospective studies to uncover the biologic mechanisms of CLL progression. To address this question, Landgren et al.(28) recently conducted a prospective cohort study based on 77,469 healthy adults who were enrolled in the nationwide, population-based, U.S. Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial.(28) The investigators identified 45 participants who were subsequently diagnosed with CLL during the period of longitudinal observation who had a pre-diagnostic peripheral blood sample available for analysis.
