B-Cell Type Acute Leukaemia

B-cell acute lymphoblastic leukaemia is a fast-growing blood cancer that primarily affects children, but adults can develop it too. With proper treatment, particularly in children, cure rates can be remarkably high.

Table of contents

• What is B-cell acute lymphoblastic leukaemia?
• Where the disease develops
• Facts and statistics
• Causes and risk factors
• Signs and symptoms
• How doctors diagnose the disease
• Treatment approaches
• What to expect

What is B-cell acute lymphoblastic leukaemia?

B-cell acute lymphoblastic leukaemia (B-ALL) is a rare blood cancer affecting the development of B-cells. B-cells are white blood cells made in the bone marrow (the soft inner part of bones). They help the body fight off infections by making antibodies^[2].

The term “acute” means the sudden and severe onset of a disorder that can progress quickly. In B-ALL, the bone marrow makes too many abnormal, immature B-cells called lymphoblasts. These abnormal B-cells build up in the bone marrow and spill over into the blood. This allows them to spread to other areas of the body quickly^[2].

The abnormal cells build up in the bone marrow and stop healthy blood cells from developing. As these immature cells increase in the blood and bone marrow, there is less room for healthy white blood cells, red blood cells, and platelets. This may cause infection, anaemia, and easy bleeding^[3].

• Bone marrow
• Blood
• Lymph nodes
• Liver
• Spleen
• Brain and spinal cord
• Testicles

Where the disease develops

B-ALL starts in your bone marrow, but it can spread throughout your body. Organs such as the lymph nodes, liver, and spleen may swell as abnormal B-cells build up in these tissues. B-ALL may also spread to the brain, spinal cord, and testicles^[2][5].

The disease develops when bone marrow cells undergo changes in their genetic material. Normally, the bone marrow produces blood stem cells that develop into mature blood cells over time. In B-ALL, too many stem cells become lymphoblasts that never mature properly. These cells are not able to fight infections like normal B-cells would^[3].

Facts and statistics

B-ALL is the most common type of childhood leukaemia. It is also the most common subtype of acute lymphoblastic leukaemia overall^[2].

Around 75% of all B-ALL cases affect children younger than six years of age. Most acute lymphoblastic leukaemia cases affect children ages 2 to 5^[2][5].

Among adults with acute lymphoblastic leukaemia, around 75% to 80% have the B-ALL subtype. B-cell acute lymphoblastic leukaemia accounts for about 85% of childhood cases^[3][5].

The outlook varies significantly between children and adults. Around 85% of children with B-ALL stay cancer free after five years. The five-year survival rate for B-ALL is above 90% in children. In adults over age 20, the five-year survival rate is around 40%^[2].

Causes and risk factors

Genetic changes cause acute lymphoblastic leukaemia. A cell’s genetic material contains the instructions that tell a cell what to do. When changes happen in this genetic material, cells can begin to behave abnormally^[6].

Researchers think changes in genes regulating B-cell development cause B-ALL. The exact cause of these genetic mutations is unknown. Young children with B-ALL may have had gene changes that happened before they were born^[2][5].

Between 60-80% of patients who develop B-cell ALL have chromosome abnormalities and gene mutations. The remaining patients do not have any detectable chromosome or gene abnormalities. Around 5% of ALL patients have a genetic syndrome associated with B-cell ALL^[7].

The chromosome abnormalities and gene mutations in patients who develop B-cell ALL are not hereditary. They are acquired during your lifetime and cannot be passed on to your children. However, patients with some inherited genetic syndromes can have an increased chance of developing ALL^[7].

The risk of developing B-ALL increases in children with^[2]:

• Family history of leukaemia, especially in other siblings
• Genetic conditions, such as Down syndrome or Fanconi anaemia
• Previous exposure to X-rays, radiation, or chemotherapy
• Suppressed immune systems, usually from treatments following organ transplantation

Other risk factors include age, with the highest risk in children under 15 and adults over 50. People who are white have a slightly higher risk. Risk also increases with exposure to radiation during foetal development or from past radiation therapy^[5].

Signs and symptoms

Signs and symptoms of B-cell acute lymphoblastic leukaemia may include^[2][5]:

• Decreased appetite or unintentional weight loss
• Difficulty breathing
• Easy bruising or excessive bleeding (especially of the nose and gums)
• Fatigue or weakness
• Pain in joints, bones, and abdomen (abdominal pain due to enlarged liver or spleen)
• Recurrent fevers or frequent infections
• Swelling of lymph nodes
• Paleness
• Night sweats
• Red, pinhead-sized bleeding spots on the skin called petechiae

Having these symptoms does not necessarily mean you have B-ALL. However, you should always talk to a healthcare provider about changes in your body that last longer than two weeks^[5].

Many signs and symptoms of acute lymphoblastic leukaemia mimic those of the flu. However, flu signs and symptoms eventually improve. If signs and symptoms do not improve as expected, make an appointment with your doctor^[6].

How doctors diagnose the disease

To diagnose B-ALL, your doctor performs a physical exam and asks about your medical history. They will want to know how long symptoms have lasted and how they interfere with everyday life^[2][5].

Tests may include^[2]:

Blood tests: These tests count the number of platelets, white blood cells, and red blood cells in a sample of your blood. Doctors also use blood tests to analyse liver and kidney function and detect signs of inflammation and infection. Blood tests may reveal too many or too few white blood cells, not enough red blood cells, and not enough platelets. A blood test may also show the presence of blast cells, which are immature cells normally found in the bone marrow^[15].

Bone marrow aspiration or biopsy: Your doctor uses a thin, hollow needle to remove small samples of bone marrow or bone tissue for analysis. This is the most common and reliable method for B-ALL diagnosis. Your haematologist will take your bone marrow sample from your hip bone. You should have a local anaesthetic and your haematologist will use a special biopsy needle^[7].

The sample is sent to a lab for testing to look for leukaemia cells. Doctors in the lab will classify blood cells into specific types based on their size, shape, and other genetic or molecular features. They also look for certain changes in the cancer cells and determine whether the leukaemia cells began from B lymphocytes or T lymphocytes. This information helps your doctor develop a treatment plan^[15].

Lumbar puncture (spinal tap): A lumbar puncture will reveal if leukaemia cells have entered your central nervous system. A member of your haematology team will insert a fine needle between vertebrae in the lumbar region of your lower back. This enables collection of a small amount of fluid for testing^[7].

Imaging tests: Imaging determines cancer severity and locates affected lymph nodes and tumours. It also detects enlarged organs, such as the liver or spleen. Imaging may include chest X-rays, computed tomography (CT) scans, echocardiograms, magnetic resonance imaging (MRI) scans, positron emission tomography (PET) scans, and ultrasounds^[2].

Treatment approaches

Doctors can treat B-ALL with chemotherapy, targeted therapy, immunotherapy, a bone marrow transplant, or a combination of these approaches^[5].

Treatment of adults with ALL traditionally consists of multiple phases. It includes a pre-treatment phase, mainly using glucocorticoids (steroids), followed by an induction phase aimed at achieving complete remission, and a consolidation phase to perpetuate the state of remission. Follow-up is either maintenance therapy or an allogeneic hematopoietic cell transplantation (allo-HCT), which is recommended for patients with a high estimated risk of disease recurrence^[17].

For B-ALL, intensive induction-consolidation chemotherapy using “paediatric-inspired” protocols is a standard of care. Allogeneic hematopoietic cell transplantation from either a human leukocyte antigen (HLA)-matched sibling, unrelated or haploidentical donor should be considered for patients with high estimated risk of relapse^[17].

Inadequate response at the level of measurable residual disease is the strongest adverse prognostic factor. Patients with B-ALL and detectable minimal residual disease should be treated with blinatumomab, a type of immunotherapy^[17].

With treatment, children have very high cure rates. Around 85% of children with B-ALL stay cancer free after five years, and the five-year survival rate is above 90% in children^[2].

What to expect

B-cell acute lymphoblastic leukaemia is a serious condition, but treatment can help. In many cases, it can cure the disease, particularly in children^[5].

The outlook depends on many factors, including age, overall health, specific genetic features of the leukaemia cells, and how well the disease responds to treatment. Children generally have much better outcomes than adults. The five-year survival rate for B-ALL is above 90% in children and around 40% in adults over age 20^[2].

Acute lymphoblastic leukaemia is the most common type of cancer in children, and treatments result in a good chance for a cure. In adults, the chance of a cure is reduced, but treatment advances continue to improve outcomes^[6].

People with B-ALL usually need to start treatment quite quickly after being diagnosed. Treatments can work well for some people with ALL, but survival depends on many factors including the type and subtype of the disease, age, and how the cancer responds to initial treatment^[3].