Chronic Myeloid Leukemia (CML)
Diagnosis & Staging

Reviewed / Updated: February 2012

Definition

CML is a myeloproliferative disease associated with the Philadelphia (Ph) chromosome and/or the BCR/ABL fusion gene. The disease is characterized by three phases: chronic phase (CML-CP), accelerated phase (CML-AP) and blast phase (CML-BP).

Diagnosis & Staging

Required tests:

• CBC and differential
• Serum creatinine, uric acid, liver function tests

• Bone marrow aspirate and biopsy with cytogenetic analysis

• Molecular analysis for BCR/ABL [quantitative PCR (QPCR)] from peripheral blood or bone marrow

The diagnosis of CML-CP requires:

1. The majority of patients present with leukocytosis and/or thrombocytosis
2. Blasts < 10% of WBCs in peripheral blood and/or nucleated bone marrow cells
3. Peripheral blood basophils < 20%
4. Hypercellular bone marrow mainly due to myeloid hyperplasia
5. Presence of Ph chromosome t(9;22) on bone marrow cytogenetic analysis and/or evidence of BCR/ABL by molecular analysis

The diagnosis of CML-AP requires one or more of the following in addition to the presence of the Ph chromosome and/or BCR/ABL positivity:

1. Blasts 10-19% of WBCs in peripheral blood and/or of nucleated bone marrow cells
2. Peripheral blood basophils ≥ 20%
3. Persistent thrombocytopenia (<100 x 10⁹/L) unrelated to therapy or persistent thrombocytosis (>1000 x 10⁹/L unresponsive to therapy
4. Increasing spleen size or WBC count unresponsive to therapy
5. Cytogenetic evidence of clonal evolution

The diagnosis of CML-BP requires one or more of the following in addition to the presence of the Ph chromosome and/or BCR/ABL positivity:

1. Blasts ≥ 20% of peripheral blood white cells or of nucleated bone marrow cells
2. Extramedullary blast cell proliferation
3. Large foci or clusters of blasts in the bone marrow biopsy

Prognosis:

A number of prognostic scoring systems have been developed to stratify patients with CML into various risk groups. The mostly widely used is the Sokal score (Blood 1984;63:789-99) or Hasford score (J Nat Cancer Inst 1998;90:850-858) . These scoring systems can provide valuable information concerning an individual patient’s prognosis and may help to guide therapy.

The information contained in these guidelines is a statement of consensus of Leukemia/BMT Program of BC professionals regarding their views of currently accepted approaches to treatment. Any clinician seeking to apply or consult these documents is expected to use independent medical judgment in the context of individual clinical circumstances to determine any patient’s care or treatment. Use of these guidelines and documents is at your own risk and is subject to the Leukemia/BMT Program of BC’s terms of use available at Terms of Use.