Some people may be genetically predisposed to certain types of leukemia. Chromosomal abnormalities are associated not only with some leukemias but also with a preleukemic disease called myelodysplasia.
Environmental risks and tobacco use also heighten the risk of developing leukemia. Also, prolonged exposure to radiation, certain chemicals, and low-frequency electromagnetic fields may raise the risk.
Because it may display no obvious symptoms, leukemia is often diagnosed incidentally during a physical exam. Doctors will recognize enlarged lymph nodes, swollen gums, and an enlarged liver or spleen as symptoms. A blood test showing an abnormally high white blood cell count is usually enough for a tentative diagnosis. To confirm diagnosis, the patient will undergo a bone marrow aspiration and bone marrow biopsy from a pelvic bone. If CML is suspected, the patient will undergo tests to detect the Philadelphia chromosome.
Doctors will also perform imaging tests in some people suspected to have leukemia. These tests include X-ray, CT scan, MRI, and ultrasound.
Although the number of leukemia cases reported has remained static since the 1950s, survival rates have improved. ALL, childhood leukemia, represents a success story. Ninety percent of children diagnosed with ALL attain remission (no more cancerous cells detected) and more than half are completely cured. In the 1960s, the five-year survival rate was 4 percent; in the 1990s, it was better than 50 percent.
Adult patients with ALL have an 80 to 90 percent chance of remission. About 40 percent who reach remission survive another five years with the chance of a full cure. Patients with AML have a 60 to 70 percent chance of remission; 20 percent survive three years with the chance of a cure.
Patients with acute leukemia almost always undergo aggressive chemotherapy to attain remission. Treatment is administered for as long as it takes to attain remission.
ALL patients may gain satisfactory remission after several weeks in the hospital. To control the disease, they will receive low-dose chemotherapy and possibly radiation for a period of time to eliminate residual traces of cancer. The amount of time spent on this phase of therapy is dependent upon the individual patient.
AML does not generally respond well to chemotherapy. The best chance of a cure is bone marrow transplantation, which requires a donor with matching tissue type and genetic characteristics—usually a family member. Bone marrow transplantation can also offer a chance at remission to people with recurring cases of ALL.
CLL treatments tend to be conservative because the disease progresses so slowly. If swelling appears in the lymph nodes or other organs, oral chemotherapy can keep the disease in check for several years. Many CLL patients lead normal lives and die of other causes.
CML can be effectively treated with oral chemotherapy for several years before the disease moves to the acute stage. Interferon, a naturally occurring protein that kills or slows the growth of cancerous cells, can lengthen CML patients’ lives. Because CML inevitably advances to the acute phase, some doctors advise a bone marrow transplant during the chronic stage.
CML is the more aggressive of the chronic leukemias. The average survival time is approximately four years because it escalates to the acute phase even while the patient undergoes treatment.