What Is Adult Acute Lymphoblastic Leukemia (ALL)?

Acute lymphoblastic leukemia (ALL) is a rare cancer accounting for less than half of one percent of all cancers in the United States. About 4 out of every 10 cases of ALL occur in adults. The following are the estimates for ALL in the United States in 2022 for both men and women (including adults and children):

Like most types of cancer, it is difficult to identify the exact cause of acute lymphoblastic leukemia (ALL). However, ALL can be linked to other conditions that might trigger it. Additionally, ALL can be caused due to gene mutations in DNA. Studies are being carried out to learn how certain changes in a cell’s DNA can cause the cell to become cancerous.

Scientists have made progress in understanding the role of DNA in causing normal cells to become cancerous. DNA is the source of instructions for everything that our cells do. 

DNA is a chemical in each of our cells and is responsible for making up our genes that provide instruction for everything that our cells do. They are packed in chromosomes, which are long strands of DNA in each cell. Most body cells have two sets of 23 chromosomes (one set of chromosomes is derived from each parent). Each sperm or egg cell has only 23 chromosomes (one set). When the sperm and egg fuse, the embryo has a standard number of chromosomes in each cell, half of which are from each parent. Two types of genes are associated with cancer development:

• Oncogenes (genes that promote cell division)
• Tumor suppressor genes (slow down cell division or cause cell death at the right time.)

DNA mutations causing the activation of oncogenes and inactivation of tumor suppressor genes can lead to cancer. Oncogenes can lead to uncontrolled blood cell production. The bone marrow creates immature cells that grow into leukemic white blood cells called lymphoblasts.

A risk factor is something that increases your risk of getting cancer. Having a risk factor or multiple risk factors does not ensure that you will get cancer. There are circumstances where people with several risk factors do not get cancer, whereas some people who get it may have few or no known risk factors. 

However, it is essential to know the risk factors to avoid acute lymphoblastic leukemia (ALL). Some of the risk factors include

• Children younger than five years and adults older than 50 years
• Male gender
• White ethnicity
• High levels of radiation exposure
• Exposure to benzene and certain chemotherapy drugs
• Infection with human T-cell leukemia virus or Epstein-Barr virus
• Genetic syndromes, such as
  • Ataxia-telangiectasia
  • Neurofibromatosis
  • Li-Fraumeni syndrome
  • Down syndrome
  • Klinefelter syndrome
  • Fanconi anemia
  • Bloom syndrome
• Having an identical twin with ALL
• Exposure to electromagnetic fields
• Smoking
• Exposure to hair dyes
• Workplace exposure to diesel, gasoline, pesticides, and certain other chemicals.

People with acute lymphoblastic leukemia may have some nonspecific symptoms, which include

• Weight loss
• Fever
• Night sweats
• Loss of appetite
• Stomach pain
• Fatigue
• Petechiae (tiny red spots just under the skin)

Symptoms that may occur due to a lack of different blood cells may include

• Tiredness
• Shortness of breath
• Weakness
• Feeling cold
• Dizziness or light-headedness
• Pale skin
• Persistent or recurring infections
• Bruises (or small red or purple spots) on the skin
• Bleeding, such as frequent or severe nosebleeds, bleeding gums or heavy menstrual bleeding in women
• Depending on the location of leukemic cells, you may also experience the following:
• Enlarged lymph nodes such as in your neck or groin, under your arms or above your collarbone
• Swollen abdomen from cancer cells in the liver or spleen
• Bone or joint pain
• Headache, trouble with balance, vomiting, seizures or blurred vision if cancer has spread to your brain
• Difficulty breathing if it has spread to your chest 

There is no standard staging system for adult acute lymphoblastic leukemia (ALL). To identify if cancer has spread to the adjoining areas, the following tests and procedures may be carried out:

• Chest X-ray: Involves an X-ray of the organs and bones inside the chest. 
• Spinal tap: A procedure where the physician collects a sample of cerebrospinal fluid (CSF) from the spinal column. The physician places a needle between two bones in the spine and directs it into the CSF around the spinal cord to remove sample fluid. These fluids are sent to check for leukemia cells in the brain and spinal cord.
• CT scan: This procedure takes detailed photos of the body from various angles and projects them in a series. A dye can be injected in a vein or swallowed to aid in better visualization of tissues and organs. Other names for scans include computed tomography, computerized tomography or computerized axial tomography.
• MRI: A procedure that uses a magnet, radio waves and a computer to take detailed photos of specific areas of the body, such as the neck and head. This is also known as nuclear magnetic resonance imaging.

ALL has different treatment stages, which include

• Untreated: When cancer is newly diagnosed and treatment focuses on symptoms rather than cancer itself. 
• Remission: In this stage, the person may have undergone treatment to destroy most leukemia cells. The complete blood count carried out may be normal and less than five percent of cells in the bone marrow are cancerous.
• Recurrent: Cancer that recurs after treatment and remission.

The treatment for acute lymphoblastic leukemia (ALL) is carried out in two phases:

1. Remission induction therapy: In this phase, the aim is to destroy the maximum number of leukemia cells in the blood and bone marrow. 
2. Post-remission therapy: This is the second phase. It begins after the initial remission induction therapy. This therapy aims to destroy any remnant leukemia cells that may be inactive initially but start to develop and cause a relapse. 

Four standard treatment options for ALL include

1. Chemotherapy: Aims to kill or destroy cancer cells while preventing their spread to other body parts. Chemotherapy can be either taken by an oral route or intravenously. The drugs enter the bloodstream to reach the cancer cells.
2. Radiation therapy: Utilizes high-energy rays to destroy cancerous cells. 
3. Targeted therapy: Aims to prevent the mutations that cause the cells to grow uncontrollably or directly attack the specific cancer cells. They are less harmful than chemotherapy or radiation therapy. Blincyto (blinatumomab) and Besponsa (inotuzumab ozogamicin) are two drugs used to treat ALL. Additionally, the FDA has approved CAR T-cell therapy that uses your immune cells to treat cancer.
4. Stem cell transplant: It is carried out after chemotherapy or radiation. In this procedure, the person gets stem cells that develop into healthy blood cells. The stem cells can be from your own body or a donor cell.

The long-term outcome of adult acute lymphoblastic leukemia (ALL) is poor. Adults are less likely to survive ALL and its aggressive treatment. Although ALL is common in children, most deaths occur in adults, about four in five cases. Adults are less likely to have a better outcome after being affected by ALL due to the following reasons:

• Adult ALL is different from childhood ALL.
• Adult bodies cannot handle aggressive treatment when compared to children.

The prognosis may also depend on various factors, including

• Lab test results: The outcome may be better if the person has a lower white blood count during the diagnosis.
• Chromosomes: People who do not have issues with their genes (such as the Philadelphia chromosome) have a better prognosis.
• Response to chemotherapy: The outcome is better if there is no evidence of leukemia four to five weeks after treatment initiation.