Prognostic variables in hairy cell leukemia after splenectomy as initial therapy

Splenectomy has been used as initial therapy in hairy cell leukemia (HCL) for many years and usually causes rapid improvement in peripheral blood counts. However, most patients eventually require further therapy. We have analyzed the case histories of 194 patients with HCL who had splenectomy as initial therapy. The median time to failure (second therapy or death) was 18.8 months. Univariate analysis of prognostic variables demonstrated that age, hemoglobin level, platelet count, bone marrow cellularity, bone marrow hairy cells, and hairy cell index (HCI) were statistically significant predictors of failure-free survival (FFS). However, only the bone marrow cellularity and platelet count were significant independent prognostic variables by Cox analysis. The patients were divided into the following three subsets by prognosis after splenectomy: (1) low risk of failure (cellularity less than 85% and platelet count greater than or equal to 60,000/microliters), (2) intermediate risk (cellularity less than 85% and platelet count less than 60,000/microliters), and (3) high risk (cellularity greater than or equal to 85%). The median FFS for each of these subsets was 56.5 months, 11.7 months, and 5.4 months, respectively. The median overall survival after splenectomy has not been reached with follow-up of up to 22 years. Patients diagnosed since 1982 have a better overall prognosis than those diagnosed earlier, with 4-year survivals of 88% and 68%, respectively (P less than 0.01). We conclude that splenectomy should continue to be the standard initial therapy in HCL. However, patients with bone marrow cellularity of 85% or greater have a short duration of response to splenectomy, and thus, may be considered for initial systemic therapy.