The clinical characteristics and outcomes of younger (≤55 years) patients with chronic lymphocytic leukemia in the era of modern prognostic biomarkers and chemoimmunotherapy are not well understood. Baseline characteristics and outcomes of patients with chronic lymphocytic leukemia ≤55 years who were seen at the Mayo Clinic between January 1995 and April 2012 were compared with those of patients >55 years. The overall survival of patients ≤55 years was compared to that of the age- and sex-matched normal population. The characteristics of 844 newly diagnosed chronic lymphocytic leukemia patients ≤55 years old (median, 50 years) were compared to those of 2324 patients >55 years old (median, 67 years). Younger patients were more likely to have Rai stage I or II disease (P
