Diagnosis

An accurate diagnosis of the type of leukemia is important. The exact diagnosis helps the doctor to

  • Estimate how the disease will progress
  • Determine the appropriate treatment

Blood Tests

After your doctor or clinician takes your blood, he or she sends it to a lab for a complete blood count (CBC), which shows the number of red cells, white cells and platelets in your blood. 

A person with CLL will have increased numbers of lymphocytes (a type of white blood cell). Low platelet counts and low red blood cell counts may also be present; these counts are usually only slightly decreased in the early stage of the illness.

Lymph Node Biopsy

Patients with enlarged lymph nodes may need a lymph node biopsy to diagnose CLL. A lymph node biopsy is a procedure in which either all or part of a lymph node is removed and examined for signs of infection or disease such as cancer.

Bone Marrow Tests

Generally, if the red blood cells and platelets are normal, a bone marrow aspiration and biopsy are not needed to make a diagnosis of CLL. However, these tests may be recommended before treatment begins. The test results can help rule out other diseases during the diagnostic stage and they can also be used later, during treatment, to evaluate the effectiveness of therapy.

Bone marrow testing involves two steps usually done at the same time in a doctor's office or a hospital:

  • A bone marrow aspiration to remove a liquid marrow sample
  • A bone marrow biopsy to remove a small amount of bone filled with marrow

Prognostic Factors

The following tests are not essential to diagnose CLL but may help predict the likely outcome or “prognosis” for the patient, assess the extent of the disease, and determine if the patient is ready for certain treatments. Numerous markers have been identified that can help segregate patients who have different rates of disease progression requiring therapy. 

Fluorescence In Situ Hybridization (FISH). This test studies chromosomes in tissue using DNA probes tagged with molecules that emit light of different colors. The DNA probes then bind to specific genes or areas in the chromosomes within the cells and light up when viewed under a microscope with a special light.

About 80 percent of CLL patients who are tested with FISH have cytogenetic abnormalities in their leukemia cells. These cytogenetic abnormalities can help the doctor identify those people with CLL who are more likely to progress to the point of requiring therapy or those who may benefit most from use of certain types of therapy.

Karyotyping. This test provides a snapshot of the chromosomes by pairing and arranging all the chromosomes of a cell in order. The test can show if there is an abnormality in the size, shape or number of chromosomes. A blood or bone marrow sample from the patient can be used. In CLL, a "complex karyotype," the presence of three or more unrelated defects in chromosomes that occur in more than once cell, is associated with a poorer prognosis. 

DNA Sequencing. This lab test uses blood or marrow samples to look for mutations in genes. In CLL, DNA sequencing is used to test for mutation in the immunoglobulin heavy chain variable (IGHV) region, and NOTCH1, SF3B1, and TP53 genes. Mutations or lack of mutations in these genes can help determine a patient's prognosis.

CLL Chromosome Changes

Your doctor will use FISH and other tests to identify chromosome changes. Knowing that a patient has chromosome changes can also help the doctor figure out the best treatment option. Below are some factors that may affect prognosis:

  • Del(13q). Some CLL patients are missing parts of chromosome 13 called “del(13q).” This is associated with a favorable outcome (if not associated with any other abnormality).
  • Del(17p)/TP53. Some CLL patients are missing parts of chromosome 17 called “del(17p)” which is linked to the mutation of the TP53 gene. Patients with the del(17p)/TP53 mutation have high-risk CLL.
  • Del(11q). Some CLL patients are missing parts of chromosome 11 called “del(11q).” This is associated with higher-risk disease.
  • +12. Some CLL patients have an extra copy of chromosome 12. This is often associated with an intermediate risk category.
  • IGHV. A mutation in the IGHV gene of CLL cells is often associated with a favorable outcome.
  • Complex karyotype. A complex karyotype is 3 or more chromosome abnormalities in the CLL cells. A complex karyotype is often associated with high-risk CLL.

 

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