Here are definitions of terms used on this website. You may find it helpful to get familiar with these words, as your doctor may use them in your conversations. The glossary also may be helpful in talking to your family and friends about Philadelphia chromosome–positive chronic myeloid leukemia in chronic phase (Ph+ CML-CP).
BCR-ABL1: An abnormal gene that creates a damaged protein by the same name. It causes the bone marrow to create leukemic cells. The BCR-ABL1 gene is formed when 2 specific chromosomes combine. The gene then creates the BCR-ABL protein—the underlying cause of Ph+ CML.
Blast cell: an immature blood cell.
Blast crisis: The final phase of Ph+ CML progression, which has the highest number of immature blood cells (blast cells) in the blood and bone marrow.
Bone marrow: A sponge-like tissue found in the center of most bones.
Chromosome: The DNA found in a cell. Human cells normally have 23 pairs of chromosomes.
Chronic myeloid leukemia (CML): A type of cancer that starts in the bone marrow, causing too many damaged white blood cells to form.
Chronic phase: The first phase of Ph+ CML progression when the number of white blood cells is higher than normal but may not cause symptoms.
Complete blood count (CBC) test: Determines if the number of white blood cells, red blood cells, and platelets are within the normal range.
Complete cytogenetic response: No Ph+ chromosomes are found in the bone marrow sample cytogenetic.
Complete hematologic response: When white blood cells, platelets, and red blood cell counts have returned to a normal range.
Cytogenetic testing: Tests done on bone marrow cells or white blood cells to see if they contain the Philadelphia chromosome
Deep molecular response (DMR): When the amount of BCR-ABL1 in the body is almost undetectable. Your doctor may call this MR4.5 (BCR-ABL1 ≤0.0032%). This means that 1 out of every 32,000 cells has the BCR-ABL1 gene.
Early molecular response: The amount of the BCR-ABL1 gene in the body is less than or equal to (≤)10% at 3 months and 6 months after starting treatment. This means that no more than 1 out of every 10 cells has the BCR-ABL1 gene.
Genetic material: The basic unit of heredity passed from parent to child. Genes are made of DNA and carry instructions for making proteins.
Hematologic testing: A simple blood test to measure levels of white blood cells, red blood cells, and platelets.
Intolerance: When a patient cannot continue taking a medication because of the side effects they are experiencing.
Leukemic cells: Diseased white blood cells that grow abnormally.
1-log reduction: The levels of leukemia cells are 10 times lower than the standardized baseline of newly diagnosed patients.
2-log reduction: The levels of leukemia cells are 100 times lower than the standardized baseline of newly diagnosed patients.
3-log reduction: The levels of leukemia cells are 1000 times lower than the standardized baseline of newly diagnosed patients.
Major cytogenetic response (MCyR): 0% to 35% of the cells in the bone marrow have the Philadelphia chromosome.
Major molecular response (MMR): When the amount of BCR-ABL1 found in the bone marrow sample or blood sample found through a PCR test is very low—specifically BCR-ABL1 ≤0.1%. This means that 1 out of every 1000 cells has the BCR-ABL1 gene.
Milestones: An optimal response or improvement reached by a certain period of time after starting treatment.
Minor cytogenetic response: More than 35% of cells in the bone marrow are Ph+ cells.
Molecular response: Refers to a decrease in the number of cells in the blood with BCR-ABL1.
Molecular testing: The use of PCR (polymerase chain reaction) to find the number of cells with BCR-ABL1 in either the blood or bone marrow.
Partial cytogenetic response (PCyR): 1% to 35% of the cells in the bone marrow have the Philadelphia chromosome.
PCR (polymerase chain reaction) test or IS-PCR test: A very sensitive test that counts the number of cells containing the BCR-ABL1 gene (which is located on the Philadelphia chromosome). It can be done on either blood or bone marrow cells and can detect a single abnormal cell within a sample of 1 million cells. IS stands for International Scale. It is a standardized scale for measuring and reporting results of PCR testing.
Philadelphia chromosome (Ph): An abnormal chromosome that is responsible for the constant production of abnormal white blood cells (myeloid cells) present in Ph+ CML. The Philadelphia chromosome indicates that CML is present in the body.
Platelets: Very small cells in the bone marrow that form blood clots and control bleeding.
Protein: An essential component of all living cells that is made up of amino acids.
Red blood cells: Move oxygen from the lungs to the body.
Resistance: When a medical condition does not respond to treatment, or stops responding to treatment.
White blood cells: Help your body fight infection and disease.