Most patients receive cladribine by IV infusion once a day for five to seven days, but more patients are being given the option of taking this drug once a week for six weeks. The different dosing schedules used with cladribine are roughly equally effective and safe. Relatively few patients have significant side effects other than fatigue and a high fever caused by the cancer cells dying, although complications such as infection and acute kidney failure have been seen. Pentostatin is chemically similar to cladribine, and has a similar success rate and side effect profile, but it is always given over a much longer period of time, usually one dose by IV infusion every two weeks for 3–6 months. During the weeks following treatment, the patients immune systems are severely weakened, but their bone marrow will begin to produce normal blood cells again. Treatment often results in long-term remission. About 85% of patients achieve a complete response from treatment with either cladribine or pentostatin, and another 10% receive some benefit from these drugs, although no permanent cure for this disease is known. If the cancer cells return, the treatment may be repeated and should again result in remission, although the odds of success decline with repeated treatment. Remission lengths vary significantly, from one year to more than twenty years. The median patient can expect a treatment-free interval of about ten years. 2-Chlorodeoxyadenosine (Cladribine) induced complete responses in patients with hairy cell leukemia resistant to DCF, suggesting a lack of cross-resistance.
Leukemic cells may gather in the spleen and cause it to swell; this can have the side effect of making the person feel full even when he or she has not eaten much.Hairy cell leukemia is commonly diagnosed after a routine blood count shows unexpectedly low numbers of one or more kinds of normal blood cells, or after unexplained bruises or recurrent infections in an otherwise apparently healthy patient.Platelet function may be somewhat impaired in HCL patients, although this does not appear to have any significant practical effect. It may result in somewhat more mild bruises than would otherwise be expected for a given platelet count or a mildly increased bleeding time for a minor cut, likely the result of producing slightly abnormal platelets in the overstressed bone marrow tissue. Patients with a high tumor burden may also have somewhat reduced levels of cholesterol, especially in patients with an enlarged spleen. Cholesterol levels return to more normal values with successful treatment of HCL. Cause
As with many cancers, the cause of HCL is unknown. Exposure to tobacco smoke, ionizing radiation, or industrial chemicals (with the possible exception of diesel) does not appear to increase the risk of developing it.