remission; the addition of rituximab, which gives the median patient only three or four years, might provide no additional value for this easily treated patient. in a more difficult case, however, the benefit from the first drug may be substantially reduced, so a combination may provide some benefit. first-line therapy cladribine (2cda) and pentostatin (dcf) are the two most common first-line therapies. they both belong to a class of medications called purine analogs, which have mild side effects compared to traditional chemotherapy regimens. cladribine can be administered by injection under the skin, by infusion over a few hours into a vein (inravenous - iv), or by a pump worn by the patient that provides a slow drip into a vein, 24 hours a day for 7 days. 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. also, 2-cda is not prohibitively toxic in patients intolerant of dcf (pentostatin). second-line therapy if a patient is resistant to either cladribine or pentostatin, then second-line therapy is pursued. monoclonal antibodies: the most common treatment for cladribine-resistant disease is infusing monoclonal antibodies that destroy cancerous b cells. rituximab is by far the most commonly used. most patients receive one iv infusion over several hours each week for 4–8 weeks. two partial and 10 complete responses resulted fromf 15 patients with relapsed disease, for a total of 80% responding. the median patient (including nonresponders) did not require further treatment for more than 3 years. this eight-dose study had a higher response rate than a four-dose study at scripps, which achieved only 25% response rate. rituximab has successfully induced a complete response in hairy cell-variant. rituximab's major side effect is serum sickness, commonly described as an "allergic reaction", which can be severe, especially on the first infusion. serum sickness is primarily caused by the antibodies clumping during infusion and triggering the complement cascade. although most patients find that side effects are adequately controlled by antiallergy drugs, some severe, and even fatal, reactions have occurred. consequently, the first dose is always given in a hospital setting, although subsequent infusions may be given in a physician's office. remissions are usually shorter than with the preferred first-line drugs, but hematologic remissions of several years' duration are not uncommon. other b cell-destroying monoclonal antibodies such as alemtuzumab, ibritumomab tiuxetan and i-131 tositumomab may be considered for refractory cases. interferon-alpha is an immune system hormone that is very helpful to a relatively small number of patients, and somewhat helpful to most patients. in about 65% of patients, the drug helps stabilize the disease or produce a slow, minor improvement for a partial response. the typical dosing schedule injects at least 3 million units of interferon-alpha (not pegylated versions) three times a week, although the original protocol began with 6 months of daily injections. some patients tolerate ifn-alpha very well after the first fw weeks, while others find that its characteristic flu-like symptoms persist. about 10% of patients develop a level of depression. by maintaining a steadier level of the hormone in the body, daily injections might cause fewer side effects in selected patients. drinking at least 2 liters of water each day, while avoiding caffeine and alcohol, can reduce many of the side effects. a drop in blood counts is usually seen during the first 1–2 months of treatment. most patients find that their blood counts get worse for a few weeks immediately after starting treatment, although some patients find their blood counts begin to improve within just 2 weeks. typically, 6 months are neededto figure out whether this therapy is useful. common criteria for treatment success include: normalization of hemoglobin levels (above 12.0 g/dl), a normal or somewhat low platelet count (above 100 k/µl), and a normal or somewhat low absolute neutrophil count (above 1.5 k/µl). if it is well tolerated, patients usually take the hormone for 12 to 18 months. an attempt may be made then to end the treatment, but most patients discover that they need to continue taking the drug for it to be successful. these patients often continue taking this drug indefinitely, until either the disease becomes resistant to this hormone, or the body produces an immune system response that limits the drug's ability to function. a few patients are able to achieve a sustained clinical remission after taking this drug for six months to one year. this may be more likely when ifn-alpha has been initiated shortly after another therapy. ifn-alpha is considered the drug of choice for pregnant women with active hcl, although it carries some risks, such as the potential for decreased blood flow to the placenta. ifn-alpha works by sensitizing the hairy cells to the killing effect of the immune-system hormone tnf-alpha, whose production it promotes. ifn-alpha works best on classic hairy cells that are not protectively adhered to vitronectin or fibronectin, which suggests that patients who encounter less fibrous tissue in their bone-marrow biopsies may be more likely to respond to ifn-alpha therapy. it also explains why unadhered hairy cells, such as those in the bloodstream, disappear during ifn-alpha treatment well before reductions are seen in adhered hairy cells, such as those in the bone marrow and spleen. other treatments splenectomy can produce long-term remissions in patients whose spleens seem to be heavily involved, but its success rate is noticeably lower than cladribine or pentostatin. splenectomies are also performed for patients whose persistently enlarged spleens cause significant discomfort or in patients whose persistently low platelet counts suggest idiopathic thrombocytopenic purpura. bone marrow transplants are usually shunned in this highly treatable disease because of the inherent risks in the procedure. they may be considered for refractory cases in younger, otherwise healthy individuals. "minitransplants" are possible. people with low numbers of red blood cells or platelets may also receive red blood cells and platelets through blood transfusions. blood transfusions are always irradiated to remove white blood cells and thereby reduce the risk of graft-versus-host disease. affected people may also receive a hormone to stimulate production of red blood cells. these treatments may be medically necessary, but do not kill the hairy cells. people with low neutrophil counts may be given filgrastim or a similar hormone to stimulate production of white blood cells. however, a 1999 study indicates that routine administration of this expensive injected drug has no practical value for hcl patients after cladribine administration. in this study, patients who received filgrastim were just as likely to experience a high fever and to be admitted to the hospital as those who did not, even though the drug artificially inflated their white blood cell counts. this study leaves open the possibility that filgrastim may still be appropriate for patients who have symptoms of infection, or at times other than shortly after cladribine treatment. although hairy cells are technically long-lived, instead of rapidly dividing, some late-stage patients are treated with broad-spectrum chemotherapy agents such as methotrexate that are effective at killing rapidly dividing cells. this is not typically attempted unless all other options have been exhausted and it is typically unsuccessful. prognosis treatment success more than 95% of new patients are treated well or at least adequately by cladribine or pentostatin. a majority of new patients can expect a disease-free remission time span of about ten years, or sometimes much longer after taking one of these drugs just once. if retreatment is necessary in the future, the drugs are normally effective again, although the average length of remission is somewhat shorter in subsequent treatments. there is also the risk of shingles, and peripheral neuropathy after treatment with cladribine. as with b-cell chronic lymphocytic leukemia, mutations in the ighv on hairy cells are associated with better responses to initial treatments and with prolonged survival. how soon after treatment a patient feels "normal" again depends on several factors, including: how advanced the disease was at the time of treatment; the patient's underlying health status; whether the patient had a "complete response" or only a partial response to the treatment; whether the patient experienced any of the rare, but serious side effects such as kidney failure; how aggressive the individual's disease is; whether the patient is experiencing unusual psychological trauma from the "cancer" diagnosis; and how the patient perceived his or her pre-treatment energy level and daily functioning. lifespan with appropriate treatment, the overall projected lifespan for patients is normal or near-normal. in all patients, the first two years after diagnosis have the highest risk for fatal outcome; generally, surviving five years predicts good control of the disease. after five years' clinical remission, patients in the united states with normal blood counts can often qualify for private life insurance with some us companies. accurately measuring survival for patients with the variant form of the disease (hcl-v) is complicated by the relatively high median age (70 years old) at diagnosis. however, hcl-v patients routinely survive for more than 10 years, and younger patients can likely expect a long life. follow-up care despite decade-long remissions and years of living very normal lives after treatment, hairy cell leukemia is officially considered an incurable disease. while survivors of solid tumors are commonly declared to be permanently cured after two, three, or five years, people who have hairy cell leukemia are never considered 'cured'. relapses of hcl have happened even after more than twenty years of continuous remission. patients will require lifelong monitoring and should be aware that the disease can recur even after decades of good health. while most oncologists consider hairy cell leukemia to be incurable, there is some evidence that some patients are in fact cured after treatments. of the original 358-patient cohort treated with cladribine at the scripps clinic, 9 of 19 in continuous cr for a median of 16 years were free of hcl mrd by flow cytometry and ihc. this suggests that the disease of at least some patients may be cured. people in remission need regular follow-up examinations after their treatment is over. most physicians insist on seeing patients at least once a year for the rest of the patient's life, and getting blood counts about twice a year. regular follow-up care ensures that patients are carefully monitored, any changes in health are discussed, and new or recurrent cancer can be detected and treated as soon as possible. between regularly scheduled appointments, people who have hairy cell leukemia should report any health problems, especially viral or bacterial infections, as soon as they appear. hcl patients are also at a slightly higher than average risk for developing a second kind of cancer, such as colon cancer or lung cancer, at some point during their lives (including before their hcl diagnosis). this appears to relate best to the number of hairy cells, and not to different forms of treatment. on average, patients might reasonably expect to have as much as double the risk of developing another cancer, with a peak about two years after hcl diagnosis