Acute lymphoblastic leukemia (ALL), also known as acute lymphocytic leukemia, is a malignant disease of the lymphoid line of blood cells. It is characterized by increased proliferation of the early lymphoid precursors that subsequently replace the normal hematopoietic cells of the bone marrow. This blood cancer typically starts in the white blood cells, invades the blood, and spreads to the other parts of the body like the liver, spleen, and lymph nodes.
What causes Acute Lymphoblastic Leukemia (ALL)?
The normal lymphoblasts generally develop into mature, infection-fighting B-cells or T-cells (lymphocytes). This process is regulated by certain signals generated in the body to ensure that an adequate number of lymphocytes are made. In ALL, however, the normal development of lymphocytes and the control over the number of lymphoid cells produced become defective.
While the exact cause is yet to be ascertained, several factors which contribute to the development of ALL have been discovered. Genetic mutations of the lymphoblast affecting blood cell development and proliferation are identified as the leading cause of ALL. In childhood ALL, this begins at conception when the child inherits some of these genes. Mutations in the ARID5B, CDKN2A/2B, CEBPE, IKZF1, GATA3, PIP4K2A, and rarely TP53 contribute to ALL development. (3), (4), (5)
Other risk factors for the development of ALL are:
· Genetic disorders like Down syndrome, Klinefelter syndrome, Fanconi anemia, Bloom syndrome, ataxia, and neurofibromatosis.
· High levels of radiation exposure,
· Treatment with chemotherapeutic drugs like epipodophyllotoxins and cyclophosphamide,
· Influenza.
What Are the Symptoms of ALL?
The initial symptoms of ALL are nonspecific and cover pale complexion, fever, recurrent infections, enlarged lymph nodes, and fatigue. The characteristic signs and symptoms (2) of ALL are:
- · Generalized weakness
- · Anemia
- · Dizziness
- · Headache, vomiting, lethargy,
- · Cranial nerve palsies
- · Frequent and unexplained fever and infection
- · Weight loss
- · Loss of appetite
- · Excessive bruising
- · Bone pain and joint pain
- · Petechiae, testicular enlargement
- · Pitting edema in lower limbs
- · Mediastinal mass
- · Breathlessness.
Screening tests: How Is Acute Lymphoblastic Leukemia Diagnosed?
The screening tests (1) used for diagnosing ALL are:
Ø Blood tests reveal the number of white blood cells, red blood cells, and platelets. The presence of blast cells, immature cells usually found in the bone marrow, can be identified through blood tests.
Ø Bone marrow test: A sample of the bone marrow is taken from the hipbone or breastbone via biopsy and tested for leukemia cells.
Ø Imaging tests: These tests identify cancer invasion to the brain, spinal cord, and other body parts. X-ray, CT-scan, and ultrasound scans are the primary imaging tests to diagnose ALL.
Ø Spinal fluid test: Spinal tap or lumbar puncture test is carried out to test whether the cancer cells have spread to the spinal fluid.
What Treatments Are Available for ALL?
The Treatment of ALL is generally categorized into different phases, such as –
Ø Induction therapy: It is initiated to kill most of the leukemia cells in the blood and bone marrow. Restoration of normal blood cell production is generally achieved in this phase.
Ø Consolidation therapy: In this phase, the remaining leukemia cells that missed out in the previous phase are killed. It is also known as post-remission therapy.
Ø Maintenance therapy: This prevents the recurrence of leukemia and is usually carried out for years.
Ø Preventive Treatment to the spinal cord includes injecting chemotherapeutic drugs directly into the spinal fluid. It is done to kill the leukemia cells located in the central nervous system.
The various treatment options:
· Chemotherapy – This initial Treatment of choice combines multiple antileukemic drugs tailored to each person. Some commonly used chemotherapeutic drugs are vincristine, cytarabine + methotrexate, etoposide, mercaptopurine, etc.
· Radiation therapy – High-powered beams such as x-rays or protons are used to kill the cancer cells. It is often recommended as a part of the preparations for bone marrow transplants.
· Biological therapy – Biological targets which elicit an effect on leukemic lymphoblasts are targeted in this method. For example, imatinib incorporated in the treatment plan of people with Bcr-AbI1+ (Ph+) ALL acts by explicitly targeting the tyrosine kinase receptor.
· Immunotherapy – This therapy takes the body’s germ-fighting T-cells, engineers them to fight cancer cells, and infuses them into the body. Also known as chimeric antigen receptor (CAR)-T cell therapy, it is frequently used for consolidation therapy or relapse treatment.
Overview:
- Acute Lymphoblastic Leukemia (ALL) is a type of cancer that begins in the bone marrow and develops when the body’s white blood cells, called lymphocytes, reproduce abnormally.
- ALL symptoms can include fatigue, pale skin, weight loss, and bruising or bleeding easily. Treatment options vary based on the severity of the disease and may include chemotherapy, radiation therapy, and stem cell transplants.
- ALL is categorized into several different subtypes. The most common is B-cell ALL, which makes up around 70% of all cases.
- However, there is also T-cell ALL, which affects about 20%-25% of all cases. There are also other rare types of ALL that make up a smaller portion, such as prolymphocytic leukemia and Burkitt’s lymphoma. Each type has its unique characteristics and treatment protocols.
