Cytogenetic changes in polycythemia vera (PV) vary by disease phase, providing the alterations in each phase with a distinct prognostic impact, according to a study involving 422 individuals.

Investigators evaluated participants who had PV in various phases. Among the results:

• One-third of patients had abnormal karyotypes; this included 20% of those in polycythemic phase and 90% in accelerated/blast phase.
• The most common abnormalities in polycythemic phase were isolated del(20q), +8, and +9.
• In post-polycythemic myelofibrosis, del(20q) and +1q were most common.
• In accelerated and blast phases, complex karyotype was most common.
• Patients with an abnormal karyotype had more frequent disease progression, shorter transformation-free survival, and inferior overall survival, vs their normal karyotype counterparts.

The authors suggested that cytogenetics be grouped this way:

• Low-risk: Normal karyotype, sole +8, +9, and other single abnormality.
• Intermediate-risk: Sole del20q, +1q, and other 2 abnormalities.
• High-risk: Complex karyotype.