Hairy cell leukemia natural history

Prognosis
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 re-treatment is necessary in the future, the drugs are normally effective again, although, statistically, the length of the remission may be somewhat shorter.

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.

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 with normal blood counts can often qualify for private life insurance with some companies.

Despite decade-long remissions and years of living very normal lives after treatment, hairy cell leukemia is officially considered an incurable disease. Relapses 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.

HCL patients are also at a slightly higher than average risk for developing a second kind of cancer at some point during their lives (including before their HCL diagnosis).

Worldwide, approximately 300 HCL patients per year are expected to die. Some of these patients were diagnosed with HCL due to a serious illness which prevented them from receiving initial treatment in time; many others died after living a normal lifespan and experiencing years of good control of the disease. Perhaps as many as five out of six HCL patients die from some other cause.

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.