Chronic Lymphocytic Leukemia.

Chronic lymphocytic leukemia, constituting approximately 30 percent of all leukemias, is the most common form of blood cancer found in industrialized countries, occurring two to three times more frequently in men than in women. The patients it affects are older than patients affected by any of the other leukemias, and the incidence increases steadily with age. In fact, it is unusual to see a patient under age sixty with this disease.

The cause of chronic lymphocytic leukemia is unknown, although strong evidence points to problems of function and control in the immune system. Diagnosis is very often discovered by accident in the course of routine blood testing for other medical reasons, since fully 25 to 30 percent of newly diagnosed patients have no symptoms. As in chronic granulocytic leukemia, for many patients the onset of symptoms is imperceptibly slow.

The course of the disease varies widely, but generally reflects the low degree of aggressiveness displayed by the malignancy. The lymphocytes that accumulate are small, long-lived, and not fully capable of performing their usual protective functions. The white blood count may be low or high, with either condition well tolerated by patients. A high white blood count does not necessarily indicate a poor prognosis. The degree of bone marrow infiltration by small lymphocytes is a much more accurate sign of degree of disease.

Enlargement of the spleen, liver, and lymph nodes is common; anemia and bleeding problems are not prominent in the malignancy, although they can occur. Diminished immune function makes infection a recurrent problem. Antibody levels run about 50 percent lower than normal and slowly decline over the course of the cancer.

Many patients with chronic lymphocytic leukemia continue to show a low-grade, symptom less abnormality of blood and bone marrow for years, leading doctors to question the value of treatment. About half of such patients are given no chemotherapy but are simply monitored at appropriate intervals. For patients with stronger symptoms, treatment with chlorarnbucil or busulfan is indicated. Either drug is effective in over 65 percent of patients, but the actual induction of a complete remission with a single agent is practically unknown. Complete remission can be achieved with multidrug regimens, but there is no evidence to support that the initial use of these more intensive schedules offers significant benefit. The tendency among oncologists is to reserve multi drug treatment for patients who do not respond to simple drug therapy. Radiation can be used to control local disease and, if needed because of anemia or simple physical problems, to reduce the size of the spleen.
Patients with chronic lymphocytic leukemia are treated for most of their course on an outpatient basis. The average life-span after diagnosis is four years. General debility and infection are the principal clinical problems experienced during the later stage of the disease. About 15 percent of patients with chronic lymphocytic leukemia will, with little or no treatment, live for another ten to fifteen years relatively untroubled by their disease.

SUMMING UP
Tremendous progress has been made over the last thirty years in treating leukemia, with an ever-increasing number of patients, especially children, now being cured of the disease. .Although the treatment is complex, lengthy, and itself produces illness, the marked success in achieving total and partial remissions makes it worthwhile for most patients.