Acute Lymphocytic Leukemia: A Common Childhood Cancer

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Acute lymphocytic leukemia (ALL) is a type of leukemia that mostly affects children, although it can affect adults as well. It is also referred to as acute lymphoblastic or acute lymphoid leukemia.  ALL affects immature lymphocytes—a type of white blood cell—known as blasts.

Overview

ALL is actually the most common cancer in children, responsible for around 25 percent of childhood cancers. Close to 7,000 people develop ALL each year with around 1,500 deaths, though roughly two-thirds of those who die are adults.

This disease is one which progresses rather quickly and is characterized by a large number of immature white blood cells in the blood and bone marrow. While in the past this was a rapidly fatal disease, it is now largely survivable with chemotherapy.

Such a description of being both aggressive and survivable at the same time can be confusing for some people, especially if you happen to read an old medical textbook which describes ALL as an extremely aggressive cancer.  Therefore, it can help to think about how chemotherapy works, by attacking the most rapidly dividing cells. 

In an era in which we have excellent chemotherapy medications, having an aggressive cancer may in some ways be considered "better," at least in the realization that we have a way to aggressively treat the disease. Tumors that are slow growing, in contrast, are less likely to be curable with chemotherapy. And while this cancer, unfortunately, occurs in children, children often do much better than adults with the disease.

What Are Lymphoblasts?

Lymphoblasts are an immature form of the type of white blood cell known as lymphocytes. In the bone marrow, a process called hematopoiesis takes place, which basically means the formation of our immune and blood cells. 

This process starts with a hematopoietic stem cell which can evolve along either the myeloid line (which then becomes a type of white blood cell known as a granulocyte, red blood cell, or platelet) or the lymphoid line.

 The lymphoblast is the "baby" in this process. Lymphoblasts can go on to become T lymphocytes (T cells), B lymphocytes (B cells), or Natural Killer Cells (NK cells.)  

Causes

It's not known exactly what causes ALL, but risk factors may include:

  • Some genetic conditions, such as Down syndrome
  • Some chromosomal changes or gene mutations
  • Exposure to substances, such as benzene
  • In utero (prenatal) exposure to x-rays
  • Exposure to treatments for cancer, including radiation therapy and chemotherapy

Symptoms

Since lymphoblasts "live" in the bone marrow, all types of blood cells including white blood cells, red blood cells, and platelets can be affected. The white blood cells which are produced—even if greater than normal in number—do not work as well as usual and there is often a decreased number of other forms of white blood cells, red blood cells, and platelets. 

Symptoms may include:

  • Fatigue and weakness
  • Pallor
  • Fever (fever of unknown origin in children) or night sweats
  • Frequent infections (this can be difficult to determine in children who normally get several infections each year)
  • Bruising
  • Shortness of breath
  • Decrease in appetite and weight loss
  • Petechiae (skin spots that appear red and do not disappear when you put pressure on the skin—do not blanch)
  • Bone and joint pain, especially in the long bones
  • Painless enlarged lymph nodes in the neck, armpits, and groin
  • Tenderness of the upper right or left abdomen, just under the ribs

Diagnosis

ALL is usually first suspected based on an increased white blood cell count with an increased number of immature lymphocytes. Further tests done in the diagnostic process may include:

  • More blood tests
  • Bone marrow biopsy
  • Imaging tests to look for tumors, especially in the abdomen, chest, or spinal cord
  • Lumbar puncture (a spinal tap is done to look for the presence of cancer cells in the cerebrospinal fluid)

Treatment

It may be helpful to understand right away that, unlike some cancers, chemotherapy for ALL is often done over a period of a few years, rather than a few weeks.

The treatment of ALL can essentially be broken down into the following stages, but usually includes intensive chemotherapy (stem cell transplants and radiation therapy are sometimes a part of treatment as well):  

  • Induction therapy (remission induction)—When ALL is diagnosed, the first step is to lower the count of blasts and restore the production of normal cells in the bone marrow. This involves aggressive chemotherapy and is sometimes done as an inpatient. When this step is done, someone with ALL is usually in remission.
  • Consolidation—The next step (considered one of the steps in post-induction therapy) is to "clean up" any cancer cells which have been "left over" after induction therapy.
  • Maintenance therapy—Even after this cancer is in remission, and further treatment has eliminated any lingering cancer cells, it has a tendency to recur without further treatment.  Maintenance therapy is designed to prevent recurrence of leukemia and result in long-term survival.
  • Prevention/CNS treatment—If ALL is present in the cerebrospinal fluid, intrathecal chemotherapy is usually done, since most chemotherapy drugs do not cross the blood-brain barrier. For many children and adults who do not have CNS involvement, treatment (including this as well as possibly radiation therapy) is done to prevent cancer from showing up or recurring in the brain.

The prognosis for children is somewhat better than adults for ALL. Currently, close to 95 percent of children achieve remission and upwards of 80 percent of children will go on to long-term survival with the disease.

Support and Coping

Often times it is a child experiencing ALL, so support needs to be directed at both the children living with ALL and their parents. Learn as much as you can about the disease. Reach out for help. Treatment for leukemia is a marathon rather than a sprint and it can help to let some of the people offering help know that you don't need it right away, but to please help out as time goes on. 

Support for children with cancer has improved dramatically over the past decade and even camps for children coping with the disease now exist all over the country. These camps help kids feel like they aren't missing out on what their peers without cancer are enjoying.

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