NCCN Guidelines for Patients® | Chronic Myeloid Leukemia
17 NCCN Guidelines for Patients ® : Chronic Myeloid Leukemia, 2018 2 Testing for CML Genetic tests Genetic tests Genetic tests for CML are done on leukemia cells. They assess for abnormal changes in genes and chromosomes. Such changes are not present at birth. Genetic tests are performed by pathologists. It often takes several days before the lab results are known. Bone marrow cytogenetics Cytogenetics is the study of chromosomes. It is used to confirm CML by testing for the Philadelphia chromosome. The pathologist will also look for other abnormal chromosomes. This will help define the CML phase. Cytogenetics may be used to assess treatment results. Treatment is working well if tests show the abnormal chromosomes are no longer present. Abnormal chromosomes reappear when treatment stops working. Karyotype A karyotype is a picture of the chromosomes in cells. See Figure 6 . For CML, a sample of bone marrow should be used. A chemical will be added to the marrow sample to start cell growth. Then, the cells will be studied with a microscope. FISH FISH ( f luorescence i n s itu h ybridization) may be performed if a karyotype can’t be done. It can assess for the BCR-ABL1 gene to confirm CML. FISH is sometimes used to assess treatment response if other tests can’t be done. FISH involves special color dyes—called probes. The probes attach to the BCR gene and the ABL gene. The BCR-ABL1 gene is detected when the colors of the probes overlap. This test can be performed on either a bone marrow or blood sample. QPCR-IS QPCR ( q uantitative reverse transcriptase- p olymerase c hain r eaction) is a test used to assess for the BCR-ABL1 gene. This test can be performed on a sample of blood or bone marrow. It is very sensitive. It can find one CML cell among more than 100,000 normal cells. A lab that uses the IS ( I nternational S cale) is advised. IS is a standardized method for measuring and reporting QPCR scores. If IS can’t be used, it is harder to compare test results from different labs. In this case, test results from the same lab is advised. Read page 29 to learn more about the IS. Figure 6 Karyotype A karyotype is a picture of the chromosomes in cells. It shows abnormal changes in chromosomes.