Acute lymphoblastic leukemia (ALL) is a type of cancer that affects the blood and bone marrow. It is called “acute” because of its aggressive nature, and “lymphoblastic” because it affects a group of white blood cells known as lymphocytes. You may have also heard ALL referred to as acute lymphocytic leukemia. While ALL is rare in adults, it is the most common type of pediatric cancer.
Treatment options for ALL include chemotherapy, targeted therapy, immunotherapy and stem cell transplants. In addition, ongoing research is leading to promising new therapies. Despite being an acute — or fast-growing cancer — ALL is considered a treatable and sometimes curable disease. In most cases, it is important to start treatment for ALL soon after diagnosis and to work with a hematologist/oncologist who specializes in the disease.
- ALL Definition
- ALL Symptoms and Causes
- ALL Risk Factors
- ALL Diagnosis and Treatment
- ALL Stages and Survival
What Is the Definition of Acute Lymphoblastic Leukemia?
Acute lymphoblastic leukemia, or ALL for short, is a type of cancer that affects the blood, bone marrow and in rare cases, other organs. It is called “acute” because of its aggressive nature and “lymphoblastic” because it affects a group of white blood cells known as lymphocytes. While ALL is rare in adults, it is the most common type of pediatric cancer.
What Is the Difference Between Acute Lymphoblastic Leukemia and Acute Lymphocytic Leukemia?
These are two different names for the same disease. These terms are used interchangeably by doctors.
What is B-Cell Acute Lymphoblastic Leukemia?
This is the most common type of ALL, and one in which the body’s B-cells are affected by the disease. When this happens, an abundance of B-cells enters the bloodstream and bone marrow. Since B-cells normally develop into cells that are critical to the body’s immune system, it might seem like having a lot of these would be beneficial to fighting off infections. However, the opposite is actually true, because B-cells affected by ALL do not function or mature properly.
What Are the Symptoms of Acute Lymphoblastic Leukemia?
The symptoms of ALL often include one or more of the following:
- bone pain
- frequent nosebleeds
- bleeding from the gums or other abnormal bleeding
- general fatigue
- weight loss
- swelling of lymph nodes under the arms or in the neck or groin
- swelling of the abdomen
- frequent infections
- shortness of breath
If you notice any unusual changes or have questions about possible ALL symptoms, talk to your doctor.
What Is the Cause of Acute Lymphoblastic Leukemia?
While the exact cause of ALL is unknown, experts have found that most cases are not inherited. Chromosomal or gene abnormalities that are acquired during life may affect the normal functioning of bone marrow to produce immature cells called blasts, which cause ALL.
What Are the Risk Factors for Acute Lymphoblastic Leukemia?
There are several known risk factors for developing ALL.
- Exposure to radiation: This includes exposure to a nuclear incident as well as previous radiation treatments for cancer.
- Chemical exposure: Occupational exposure to certain chemicals such as benzene may increase the risk of ALL.
- Genetic diseases: While most cases of ALL don’t seem to be inherited, if you have one of a number of genetic syndromes, your chances of getting ALL may be higher. These include Down syndrome, Klinefelter syndrome, Fanconi anemia, Bloom syndrome, Ataxia-telangiectasia, Neurofibromatosis and Li-Fraumeni syndrome.
- Age: ALL is most common in children, followed by adults over age 50.
How Is Acute Lymphoblastic Leukemia Diagnosed?
Generally, an ALL diagnosis is determined by testing both the blood and the bone marrow, with a biopsy of the latter acting as the most definitive test. If you develop ALL symptoms, your doctor may request these measures.
Physical Exam: Your doctor will likely start with a physical exam, which usually includes questions about your family medical history, pre-existing conditions and overall health.
Complete Blood Count (CBC): Patients with ALL have elevated white blood cell counts and lower than normal numbers of red blood cells and platelets. Blast cells — immature cells circulating in the blood that are normally in bone marrow — may also be present. So after a physical exam, a CBC is likely the first test your doctor will order.
Peripheral blood smear: Often referred to as a “smear,” this test examines a drop of blood under a microscope, looking for abnormal cell appearances that may signal the presence of ALL.
Bone Marrow Biopsy: While blood tests may sometimes be able to signal the presence of leukemia, a bone marrow biopsy is the definitive method to diagnose ALL. There are two parts to the procedure: bone marrow aspiration and biopsy. The procedure itself is an office procedure lasting for 15-20 minutes. A local anesthetic is injected to numb the skin and covering of the bone called the periosteum. During the biopsy procedure, a small amount of bone marrow tissue will be withdrawn with a needle (aspiration) and a marrow core (biopsy) will be taken from the hip bone. The sample will then be examined under the microscope to confirm the diagnosis of ALL. The sample is also tested for various genetic and chromosomal changes.
Can ALL Be Diagnosed Early?
There are no tests or screening processes for detecting ALL early. Because the symptoms of leukemia are similar to those of other diseases, like influenza, ALL can sometimes take a while to diagnose. For people who fall into higher risk groups (such as those with genetic syndromes or who have been exposed to radiation), doctors often recommend regular medical checkups with these diseases in mind.
I’ve Been Diagnosed with Acute Lymphoblastic Leukemia, Now What?
It’s important to understand what type of ALL you’re dealing with, whether it’s B-cell, T-cell or one of the other subtypes. By this time, most patients diagnosed with ALL will be under the care of a doctor specialized in hematology/oncology. Ask your treating doctor about your exact diagnosis, subtype and if there are any genetic mutations that could be targeted. Also, inquire about the prognosis and goals of treatment. This discussion will help guide you and your family in making an informed choice about the treatment, in consultation with your doctor.
What Is the Treatment for Acute Lymphoblastic Leukemia?
The “acute” in acute lymphoblastic leukemia means the disease progresses quickly, so most patients diagnosed with ALL will need to start treatment right away.
Common ALL treatments include:
- Chemotherapy is the use of strong drugs to kill or damage cancer cells. It is the primary treatment for most people with ALL because this disease is a blood cancer and chemo drugs travel through the bloodstream to reach other parts of the body. There are usually three phases of chemotherapy treatment for ALL:
- Induction: The goal of this first phase is to achieve remission. It can be intense and often requires a hospital stay, but it is very effective. Induction usually lasts for about a month.
- Consolidation: This phase, also called intensification, usually occurs after the ALL is in remission. It is the most intense of the three phases and often lasts for several months.
- Maintenance: Patients are usually given follow up 6-mercaptopurine (6-MP) and methotrexate, in addition to vincristine and a steroid (prednisone or dexamethasone). This phase is less intensive and can last for about two years.
- Targeted therapy in ALL is the use of drugs that work by attacking a specific gene mutation or a cell protein. Roughly one in four patients with ALL develop an abnormal protein that comes from the swapping of genetic material between chromosomes 9 and 22. This protein helps cells grow quickly. To impede this, drugs called tyrosine kinase inhibitors (TKIs) are given to patients. These include imatinib (Gleevec), dasatinib (Sprycel), nilotinib (Tasigna), ponatinib (Iclusig) and bosutinib (Bosulif).
- Immunotherapy boosts the patient’s own immune system or uses monoclonal antibodies, which are man-made versions of antibodies, to target a specific protein, such as those on the surface of leukemia cells. Common immunotherapy drugs for ALL include blinatumomab (Blincyto) and inotuzumab ozogamicin (Besponsa).
- CAR-T (Chimeric antigen receptor T-cell) therapy is a novel way of treating B-ALL. In this therapy, a patient’s own immune cells called T-cells are collected. These cells undergo genetic engineering to make them specifically targeted to kill cancer cells. These cells are infused back to the patient after the patient receives a type of chemotherapy called lymphodepletion chemotherapy (typically a combination of fludarabine and cyclophosphamide). Patients are then monitored for complications of CAR-T therapy including cytokine release syndrome (CRS) and neurological complications.
- Stem cell transplants are generally used in combination with high doses of chemotherapy. As chemotherapy kills off cancers, it also damages the patient’s bone marrow. After a large dose of chemotherapy is given to a patient, many will then receive a stem cell transplant to help encourage the growth of new, healthy bone marrow.
Additionally, here are a few questions to ask when discussing treatment options with your doctor:
- What type of ALL do I have?
- Which treatment do you recommend, and why?
- How long does the treatment last?
- What are the risks and side effects of treatment?
- How do I know if I am cured?
- How can I keep myself safe from getting an infection?
- What is my prognosis?
What Are the Stages of Acute Lymphoblastic Leukemia?
Because ALL does not form tumors, it isn’t staged like other cancers. Instead, the subtype of ALL and whether or not the leukemia has spread beyond the blood and bone marrow are the two pieces of information used to inform a patient’s treatment plan and prognosis. If you don’t know which subtype of ALL you have, ask your doctor. The World Health Organization (WHO) classification is often used to define the ALL subtype.
What Is the Survival Rate of Acute Lymphoblastic Leukemia?
The relative five-year survival rate from 2010 to 2016 was 68.8% according to Surveillance, Epidemiology, and End Results (SEER) data published by the National Cancer Institute. This means that approximately 69 out of 100 people diagnosed with ALL were still alive five years after their diagnosis. This number is quite high when compared to other cancer types, and survival rates are constantly improving as new and better treatments are discovered. In fact, as recently as 1975, the survival rate for all forms of ALL was under 40%. Regular medical advancements are making progress.