Helping Develop New Leukemia Classification

Ruzanna Harutyunyan's picture
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Ohio State University leukemia researcher Dr. Clara D. Bloomfield is among a small group of cancer clinicians who helped revise the World Health Organization’s classification of leukemias and lymphomas.

The “WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues” is used by oncologists and pathologists worldwide for the histologic and genetic typing of tumors, and for designing clinical studies that monitor responses to therapy and clinical outcomes.

The recently published classification includes the use of molecular and genetic markers in leukemia cells to determine patient prognosis and treatment to a much greater degree than the previous classification, published in 2001.

Bloomfield, an internationally renowned acute-leukemia specialist at The Ohio State University Comprehensive Cancer Center, chaired the clinical advisory committee for the section on myeloid tumors.

She was one of only a few clinicians among the 130 authors from 22 countries who were invited to help write the new guide.

“The new acute myeloid leukemia (AML) classification is much more heavily based on chromosomal and molecular findings in patients’ leukemia cells,” says Bloomfield, who for 30 years has led research that discovered many of the chromosomal and molecular markers incorporated into the AML classification or that helped establish their prognostic significance.

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“Over two-thirds of AML cases are now diagnosed based on genetic findings, as compared with about one third of cases before this.”

This change has important clinical significance, she says. “It enables us to identify patients who require different therapies for cure or improved survival. This also enables us to categorize patients who can be treated using molecularly targeted therapies.”

Prior to 2001, leukemias were diagnosed largely on how the leukemia cells look under the microscope.

“This is pretty subjective, but some groups continue to use it,” says Bloomfield, a Distinguished University Professor. “The new classification will help eliminate the use of that system, and it will make clinical trials in leukemia findings much more comparable worldwide.”

Notable changes incorporated into the 2008 WHO AML classification include the following:

* AML is now divided into six major subgroups; previously there were five.

* “AML in children with Down syndrome” now forms a separate subgroup. “Children with Down syndrome who develop AML have a more favorable outcome compared with other children who develop AML,” Bloomfield notes.

* The largest subgroup, “AML with recurrent genetic abnormalities,” which represents about 55 percent of adult AML cases, is now divided into seven subtypes, rather than the previous four. In addition there, are two provisional subtypes identified solely using molecular markers, “AML with a mutated NPM1 gene,” and “AML with a mutated CEBPA gene.”

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