The International Working Group (IWG) listed criteria for disease progression following therapy for myelofibrosis with myeloid metaplasia. The work was based on a study by the International Working Group for Myelofibrosis Research and Treatment (IWGMRT).


Patient selection: myelofibrosis with myeloid metaplasia


Criteria for disease progression - one or more of the following:

(1) progressive splenomegaly (see below)

(2) leukemic transformation with the bone marrow blasts >= 20%

(3) increase in the absolute peripheral blood blast count by >= 20% for >= 8 weeks (ratio of current to baseline blast count >= 120%)


ratio of current to previous blast count =

= (current blast count) / (previous blast count) * 100%

Spleen on Previous Exam

Progression If the Spleen Is

no splenomegaly

> 5 cm below left costal margin

palpable at 5 to 10 cm below costal margin

ratio in palpable distance >= 200%

palpable at > 10 cm below costal margin

ratio in palpable distance >= 150%



• The data for splenomegaly is unclear if it is palpable 1-4 cm below the left costal margin.


ratio of palpable distance for spleen below left costal margin =

= (current palpable extent in cm) / (previous palpable extent in cm) * 100%


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