Question
Which is the most accurate test for evaluating the effectiveness of treatment in chronic myeloid leukemia (CML)?
| A. |
CBC (Complete Blood Count) |
| B. |
Cytogenetic test |
| C. |
RT-PCR (Reverse Transcriptase Polymerase Chain Reaction) |
| D. |
FISH (Fluorescence In Situ Hybridization) |
|
Correct Answer » C Explanation |
 |
RT-PCR detects and quantifies BCR-ABL1 transcript levels with very high sensitivity (up to 1 leukemic cell in 10⁵–10⁶ cells).
→ Most accurate method to monitor treatment response and minimal residual disease (MRD) in CML.
Cytogenetic test (karyotyping)
Detects Philadelphia chromosome but has lower sensitivity than RT-PCR; useful for initial response, not best for ongoing monitoring.
FISH
More sensitive than cytogenetics but less sensitive than RT-PCR; cannot quantify very low disease burden.
CML monitoring hierarchy (remember this):
CBC < Cytogenetics < FISH < RT-PCR
Harrison’s Principles of Internal Medicine (21st ed.)
“Quantitative RT-PCR for BCR-ABL transcripts is the most sensitive method for monitoring response to therapy in chronic myeloid leukemia.”