The presence of derivative chromosome 9 deletions shortens length of chronic phase and survival. Shown are 2 Kaplan-Meier graphs for a cohort of 241 patients with duration of chronic phase and survival compared according to deletion status. Log-rank analysis demonstrates significantly shorter duration of chronic phase and overall survival for those patients who carry deletions (median follow-up was similar for both groups, at 31 months for patients who carried deletions and 34 months for those without a deletion). Data shown are from Huntly et al⁵⁰  with permission and B.J.P.H., unpublished observations, June 2002.