Clinical implications of ZAP-70 expressionin chronic lymphocytic leukemia.

Chronic lymphocytic leukemia (CLL) is a disease with an extremely heterogeneous prognosis. Because of this and because of the lack of a truly effective therapy, treatment of CLL must be adapted to the individual risk of each patient. Over the last quarter of century, prognosis of patients with CLL has been based on clinical features. In the last few years a number of biological prognostic parameters have been identified. Among them, the expression of ZAP-70 in neoplastic B lymphocytes is increasingly being recognized as of paramount importance to predict outcome. Patients with a low percentage (<20%) of ZAP-70 positive neoplastic B lymphocytes have a much better prognosis that those with a higher proportion (>20%) of ZAP-70 positive neoplastic B lymphocytes.