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 patients 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 and falling steadily after that, assuming that the HCL was successfully treated. Aggressive surveillance and prevention efforts are generally warranted, although the lifetime odds of developing a second cancer after HCL diagnosis are still less than 50%. There is also a higher risk of developing an autoimmune disease. Polyarteritis nodosa has been associated with underlying hairy cell leukemia in certain cases.
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.