Cytogenetics is the most critical prognostic factor in AML. Cytogenetic abnormalities including losses involving the long arms of chromosome 5 and 7 and the short arm of chromosome 17 or a complex karyotype (defined as greater than or equal to 3 unrelated abnormalities) confer an adverse prognosis. TP53 mutations are seen in AML and are often associated with a complex karyotype and poor response to therapy regardless of cytogenetic analysis.
Our study examines a retrospective AML cohort for the relationship between p53 protein expression by IHC and karyotype of the leukemia cells. p53 IHC staining was performed on bone marrow clot and biopsy sections from AML patients diagnosed from January 2007-January 2009 and with successful cytogenetic analysis done by standard methods.
Results: 179 patient samples met inclusion criteria for our study. P53 was positive in 29 cases (16%). In p53 positive cases there is an 89.7% chance the leukemic blasts will have a complex karyotype. G-banding is still crucial for prognosis due to low sensitivity of p53 IHC. IHC for p53 is useful in the prompt initial diagnostic workup of this aggressive disease.
Investigator, CHEO Research Institute