What is the difference between acute and chronic lymphocytic leukemia?

Symptoms

Many cases of CLL can occur without symptoms. A doctor may identify the condition while performing a blood test for another health issue.

ALL typically causes immediate symptoms that resemble the flu:

• tiredness
• lightheadedness and dizziness
• pale skin
• body aches
• headaches
• vomiting
• loss of appetite

Both forms of leukemia can cause problems that relate to low blood cell counts, including anemia and leukopenia.

These issues can occur within days or weeks of ALL but not until the later stages of disease progression in chronic cases. Symptoms could include:

• pale skin
• recurring infections and infections that do not go away
• easy bleeding and bruising, such as bleeding gums and severe nosebleeds
• fevers and night sweats
• spleen enlargement, causing feelings of fullness in the abdomen
• liver enlargement
• enlarged lymph nodes
• bone or joint pain

Can acute become CLL or vice versa?

There are no scientific studies that report ALL becoming chronic.

CLL does not typically transform into acute leukemia, though reports of rare cases exist. The condition is more likely to undergo Richter’s syndrome, where it develops into a more aggressive form of lymphoma.

Causes

Genetic mutations that occur after birth, and are therefore nonhereditary, cause acute and chronic cases. These mutations activate genes that increase cell growth and division while deactivating genes that slow cell growth and cause cell death.

Some types of genetic mutations in ALL and CLL are the same, while others may be more prevalent in one or the other.

According to a 2017 study, around 80% of CLL patients have at least one of four common chromosomal alterations or deletions. The most common is the deletion of part of chromosome 13, but it can also affect chromosomes 11 and 17. It can also affect an extra chromosome, known as trisomy 12, and other less common irregularities.

Translocation is the most common form of chromosomal change in ALL. This means that the DNA from one chromosome breaks away and attaches to another. The most common translocation in adult ALL relates to the Philadelphia Chromosome, a break in DNA between chromosomes 9 and 22. Experts often note this as 9:22.

Risk factors

According to the American Cancer Society (ACS), CLL is the most common type of leukemia in American adults. Some risk factors for ALL or CLL leukemia include:

• Age: Acute cases are more common than chronic cases in children, but men over 50 are the highest risk group for both conditions.
• Race and ethnicity: People in Europe and North America are at higher risk for CLL than those in Asia. However, acute cases are more common in white than African American people.
• Family history: A person with an identical twin who has ALL has an increased risk of developing the condition. Having a first-degree relative with CLL could double the risk of someone developing the condition.
• Chemical exposure: CLL has links to long-term exposure to certain herbicides, chemotherapy drugs, and benzene.

Other risk factors for ALL include exposure to radiation and genetic syndromes, such as Down syndrome. Some viruses, such as the Epstein-Barr virus, can also cause the condition.

Diagnosis

Doctors will perform a thorough physical examination and medical history check to identify symptoms and risk factors for leukemia. They may order blood tests, such as a complete blood count with a blood smear.

People with ALL will have too many immature white blood cells, but chronic cases cause excess mature cells.

Taking bone marrow samples and biopsies are also important for diagnosing both conditions. Specialists will assess these samples for atypical structures or numbers of blood cells. They will also check for markers of leukemia to determine the type of leukemia and its progression.

Doctors will also use chromosome testing to check for mutations.

Treatment

People with CLL may not require treatment, but doctors will closely monitor the disease progression and symptoms.

Both conditions have similar treatments, which include:

• chemotherapy
• immunotherapy
• targeted therapy
• monoclonal antibodies
• stem cell transplant

Although doctors treat both ALL and CLL with similar medications, the specific drugs and their intensity will vary greatly.

Outlook

There are no cures for either CLL or ALL. However, people with CLL typically have a positive prognosis and can survive for years without treatment. Most individuals will eventually require some treatment, which may occur in cycles.

The survival of those with ALL will depend on various factors, including age, disease progression, and health status. People with the condition typically respond well to treatment, including children.

The 5-year survival rate for ALL is 90% for those under 15 years old and over 75% for those aged 15 to 19 years.

The National Cancer Institute estimates that both adults and children with ALL have around a 70% 5-year survival rate. The ACS suggests that around 80–90% of adults with ALL will have complete remissions after treatment.

Prevention

ALL and CLL are cancers that develop due to genetic mutations that are difficult to prevent. However, avoiding exposure to radiation, tobacco products, and benzene could help lower the risk.

For example, a 2021 study found that children with exposure to parents who smoke were more likely to develop ALL. Another 2021 study found that most acute cases that develop in infants begin before birth.

A review paper suggested that most children with a genetic mutation that increase the risk of leukemia remain healthy. This finding highlights the importance of a second mutation or environmental factors for triggering leukemia.

Summary

ALL and CLL share similar causes, symptoms, and treatments. However, the disease progression and outlooks are substantially different. Acute cases develop rapidly and require immediate treatment, whereas chronic cases develop more slowly.