Functional criteria for staging and treatment of hairy cell leukemia.

The determination of clinical stage in hairy cell leukemia is hampered by the lack of common criteria. Furthermore, clinical stages in which the disease should be treated have not yet been defined. In this paper we propose common criteria for the clinical staging of all hairy cell leukemia patients (treated or untreated), as well as for the assessment of responses to therapy. These criteria are absence or presence of disease-related symptoms and disease progression. Based on these criteria we propose that hairy cell leukemia patients in the most favorable stage of the functional system, non-symptomatic Stable Disease (nsSD), do not require treatment. Only in patients with disease-related symptoms and/or signs of disease progression is treatment justified and necessary. No symmetry was observed between the functional stages and Jansen's stages. For evaluation of responses to treatment, our stages were more sensitive than the Leeds criteria. Experimental evidence enables the differentiation of patients with non-symptomatic stable disease from those with symptomatic and/or progressive disease.