Acute Lymphoblastic Leukemia


The condition acute lymphoblastic leukemia is the most common type of leukemia found in children. This conditions accounts for around 26% of all cancer cases in children up to 14 years old [1, 2].

What is Acute Lymphoblastic Leukemia ?

Acute Lymphoblastic Leukemia or ALL, is a cancer that affects the bone marrow. In this condition, the normal cells found in the bone marrow are changed with early lymphoid precursors or lymphoblasts. These precursors failed to grow into mature bone marrow cells which results to a decrease in the production of normal blood cells.

The stop in their development is caused by abnormalities in gene expressions that are caused by translocations in the chromosomes. The lymphoblasts not only proliferate in the bone marrow but may also accumulate in other organs such as lymph nodes, spleen and liver. The decrease in the production of normal blood cells may lead to conditions such as neutropenia, thrombocytopenia and anemia [1, 2].

Acute lymphoblastic leukemia blood stem cells


Staging

The French-American-British system classify ALL into 3 stages based on the histological characteristics of the lymphoblasts found in the system of the patient [2, 3].


ALL-L1

They are small cells that has the following characteristics: mild to moderate basophilia, regular nuclear shape, scanty cytoplasm, homogenous nuclear chromatin and small or no nucleoli [2].

ALL-L2

The large heterogeneous cells have a variable basophilia, irregular nuclear shape, amount of cytoplasm varies, have 1 or more nucleoli and varying nuclear chromatin [2].


ALL-L3

The lymphoblasts found in this stage are huge, homogenous cells with a regular nuclei, fine, stippled chromatin, a prominent nucleoli and a cytoplasm that is deeply basophilic. The most distinguishable characteristic of these lymphoblasts its prominent cytoplasmic vacuolation [2].

Causes

Cancers are found to be caused by DNA changes because they may activate oncogenes and deactivate tumor suppressing genes. Translocation of chromosomal segments is the most common type of cellular change that is associated with leukemia. In this process, a segment of a chromosome breaks off and attaches to another chromosome. The point where the chromosome broke can affect oncogenes or deactivate genes that is essential to the normal maturation of cells. Other changes in the DNA which can affect other genes are inversion and deletion [3].

Risk Factors

There are several known risk factors for this type of leukemia. Possessing these factors is not a guarantee that a person will develop ALL, it just increases the likelihood of developing the disease. Some of these factors include previous chemotherapy and radiation therapy treatment, having a sibling with ALL and genetic conditions such as Down syndrome [4, 5].

Signs and Symptoms

Patients with ALL may exhibit signs and symptoms that is related to low number of white blood cells, red blood cells and platelets. They may experience easy fatigability, appearance of pinpoint dark-red spots due to bleeding, appearance of lumps in the underarm, neck, groin or stomach and loss of appetite. These symptoms are very similar to that of flu so a physician might not be consulted right away. If the symptoms did not improve, a physician must be seen right away [4, 5].

Diagnosis

Health history and physical examination

A physician must take note of the patient’s health habits and past illnesses to identify the potential problem. The physical examination will include an assessment of the body for other signs and symptoms [6].

Complete blood count

If ALL is suspected, the physician may perform a complete blood count to the patient. A fresh blood sample will be collected and its component will be analyzed. This test will be able to identify the quantity of RBCs, number and type of WBCs and the number of platelets in the blood [6].


Bone marrow aspiration and biopsy

A sample of a bone marrow is obtained by inserting a hollow needle in the patient’s breastbone or hipbone. The sample obtained will be examined under a microscope. This diagnostic procedure will show the presence of cancer cells in the bone marrow [6].

Spinal fluid test

A procedure called a spinal tap may be performed to collect a sample of the spinal fluid. Examination of this fluid will tell if the cancer cells have spread to the brain and the spinal cord [4, 6].

Treatment

The treatment for ALL in children is performed in different phases [4, 6].

Remission induction

This is the first part of the treatment and the goal is to eliminate all the cancer cells found in the bone marrow and blood. After this, the leukemia will go into remission [4, 6].

Consolidation

This phase will once the disease is in remission. This part of the treatment will eliminate any remaining cancer cells in the body [4, 6].

Maintenance

In the maintenance phase, a lower dose of cancer treatment is given to kill cancer cells which may grow again and cause a relapse. It is important to follow through to this part of treatment to reduce the chance of cancer coming back [4, 6].

Treatment standards

There are 3 types of standard treatment that may be used to treat ALL [4, 6].

Chemotherapy

Antineoplastic drugs are administered to the patient either orally or intravenously to treat leukemia. When these drugs go into the system, the cancer cells will either die or stop from dividing further [4, 6].

Radiation therapy

High energy beams such as x-rays are used to halt the growth of cancer cells or eliminate them. The radiation is either delivered by machine of by an implant that is near the cancer site [4, 6].

Chemotherapy with stem cell therapy

A transplant of stem cells may be done in combination with chemotherapy. The stem cells is obtained from a donor and infused with the patient [4, 6].

Survival Rate and Prognosis

The 5-year survival rate for patients with acute lymphoblastic leukemia is at 70%. This is the median rate and there are variations between different age groups. The rate is highest in patients who are less than 14 years of age (90%) while lowest in those who are 65 years old and older (15%).

Factors which may affect the patient’s outcome include the type of white blood cell that is affected and the number of white blood cells in the blood before the treatment was initiated. The more WBCs present in the blood, the poorer is the outcome for the patient. The prognosis is also poor if the leukemia cells have already spread to the brain and the spinal fluid.

References

  1. Be The Match. (2015). Acute lymphoblastic leukemia (ALL). Retrieved from Be The Match: https://bethematch.org/for-patients-and-families/learning-about-your-disease/acute-lymphoblastic-leukemia/
  2. Seiter, K. (2015, December 3). Acute Lymphoblastic Leukemia (ALL) Guidelines. Retrieved from eMedicine: http://emedicine.medscape.com/article/2249076-overview
  3. American Cancer Society. (2014, December 9). Leukemia–Acute Myeloid (Myelogenous). Retrieved from American Cancer Society: http://www.cancer.org/cancer/leukemia-acutemyeloidaml/detailedguide/leukemia-acute-myeloid-myelogenous-classified
  4. Mayo Clinic Staff. (2016, January 28). Acute lymphocytic leukemia. Retrieved from Mayo Clinic: http://www.mayoclinic.org/diseases-conditions/acute-lymphocytic-leukemia/basics/risk-factors/con-20042915
  5. Movva, S. (2015, April 26). Acute Lymphoblastic Leukemia. Retrieved from Web MD: http://www.webmd.com/cancer/lymphoma/acute-lymphoblastic-leukemia?page=2
  6. National Cancer Institute. (2015). Childhood Acute Lymphoblastic Leukemia Treatment (PDQ®)–Patient Version. Retrieved from National Cancer Institute: http://www.cancer.gov/types/leukemia/patient/child-all-treatment-pdq

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