Acute Lymphocytic Leukemia Health Article

Demographics

ALL is less common than AML in adults; about 1500 adults are diagnosed with ALL each year, compared to 10, 000 diagnosed with AML. About 1000 adults die of ALL each year and the overall five-year survival rate for adults with ALL is 58%.

About 1500 cases of ALL are diagnosed in children under 18 each year in the United States. ALL is by far the more common form of leukemia in children. The death rate for children with ALL has dropped nearly 60% in the last 30 years. The overall five-year survival rate for children with ALL is now 80%. Still, leukemia causes more deaths in children under 15, about 550 per year, than any other disease.

In the United States, ALL is highest among Caucasians and lowest among Asian-Americans. The incidence of ALL is about 50% higher for men than for women. Death rates in leukemia patients are highest in African-Americans and Caucasians and lowest in Asians.

In children, the highest leukemia rates in the US occur among those of Filipino descent; next highest are white Hispanics, then non-Hispanic whites, and the lowest incidence in children is in African-Americans. Survival is higher for Caucasians than African-Americans. The survival rate for girls is slightly higher, in part due to the risk of relapse occurring in the testicles and in part because boys appear to have a slightly higher risk of bone marrow relapse.

Causes and symptoms

Causes

While specific causes for ALL are not known, there are some known risk factors, including ionizing radiation. Exposure to certain chemicals, particularly benzene (used in the manufacture of plastics, rubber, and some medicines), has also been associated with an increased risk of developing ALL. ALL incidence in adults increases with age.

The causes of ALL in children are also unknown. Certain inherited genetic abnormalities, such as Down syndrome, increase the risk. Some studies have shown prenatal exposure to ionizing radiation increases a child's risk of ALL. Some contaminants of tap water, such as trihalomethanes, chloroform, zinc, cadmium, and arsenic are associated with an increased risk. A number of reports suggested an increased risk of ALL among children who lived in proximity to high voltage power lines, but several later analyses suggested that was not true. Studies continue in efforts to disprove or confirm this possible connection. ALL is more common in children who are not firstborn and among those whose mothers took antibiotics during their pregnancies. Breastfeeding has been found to be protective.

Symptoms

ADULTS.

ALL in adults can cause any or all of the following symptoms:

• fevers, chills, sweats
• weakness, fatigue, shortness of breath
• frequent infections
• depressed appetite, weight loss
• enlarged lymph nodes
• easy bleeding or bruising
• rash of small, flat red spots (petechiae)
• bone and joint pain

Symptoms of central nervous system involvement include:

• headache
• nausea and vomiting
• confusion
• seizures

CHILDREN.

Symptoms in children are similar, but young children may be unable to communicate them. They include:

• fevers
• frequent infections
• fatigue, irritability, decreased activity levels
• easy bruising or bleeding
• bone or joint pain
• a limp
• swollen belly
• enlarged lymph nodes

T-cell ALL can invade the thymus gland in the upper chest, which can cause compression of the windpipe, cough or shortness of breath, and superior vena cava syndrome (compression of a large vein that causes swelling of the head, neck, and arms).

Central nervous system involvement in children produces:

• headache
• nausea and vomiting
• blurred vision
• decline in school performance
• seizures

Spread to the testicles can cause painless swelling in them.

Diagnosis

There are no screening tests for leukemia. The patient's history and physical examination raise the physician's suspicions, triggering orders for appropriate tests. Pallor, swollen lymph nodes, bleeding, bruising, pinpoint red rashes, and in children, a swollen abdomen, will suggest the diagnosis. Testing is similar for adults and children.

The first test is a complete blood count (CBC), examining red cells, platelets and white cells. In early leukemia, the total white blood cell count might be normal, but there will usually be circulating lymphoblasts, which is always abnormal. The red cell and platelet counts may be low.

The abnormal CBC results trigger a referral to a hematologist/oncologist who will perform a bone marrow aspiration and biopsy, in which a small sample of marrow is removed with a hollow needle inserted in the hipbone. Although topical anesthetic will numb the skin and bone, most patients experience brief pain during this procedure. The sample will be examined microscopically for evidence of lymphoblasts. The marrow will be further studied to determine whether the lymphoblasts are of T-cell or B-cell origin and the cells tested for chromosomal abnormalities. A pathologist can examine the marrow and make the diagnosis immediately. The chromosome studies require several days to complete. The bone marrow aspirate will be repeated occasionally during treatment to confirm remission and to look for possible relapse.

A lumbar puncture, or spinal tap, will be performed to rule out spread of ALL to the central nervous system. A thin needle is inserted between two vertebrae in the lower back, and spinal fluid removed. This fluid is examined microscopically for the presence of lymphoblasts. Topical anesthetics eliminate most of the discomfort of a spinal tap, although many patients experience headaches afterwards. Remaining flat for 30 minutes after a spinal tap decreases the likelihood of headache.

A chest x ray will show enlargement of internal lymph nodes or the thymus gland.

No preparation is necessary for most of the testing done to diagnose ALL. Younger children will often receive mild sedatives before procedures like spinal taps and bone marrow studies. Topical anesthetic cream can be applied an hour in advance of either a bone marrow test or a spinal tap.

When treatment is complete, tests for minimal residual disease can be performed. These new tests detect the presence of lingering leukemic cells that would have been missed by standard testing. The presence of a certain amount of residual disease probably has an impact on prognosis and the likelihood of relapse.