Progression to therapy requirement for asymptomatic patients after diagnosis of 17p− CLL. (A) The 3 year progression rate to therapy requirement was 53% for the study cohort. (B) Progression to therapy requirement by institution. The 3-year progression rate to therapy requirement was 56% for patients from MDACC and 47% for patients from the Mayo Clinic (P = .17). (C) Progression to therapy requirement, effect of clone size. Patients with 75% or more nuclei with 17p− were at increased risk of progression (79% at 3 years vs 40% for the remaining patients, P = .001). (D) Model for progression to first therapy. Risk factors were Rai stage 1 or higher, and unmutated IgVH gene. Patients with 0, 1, and 2 risk factors had 3-year progression rates of 0%, 54%, and 100%, respectively (P < .001). Thirteen patients were not assessable due to missing data on IgVH status.