What is leukemia and what are its types? What are overall survival rates by age?

What is leukemia?

Leukemia is a type of cancer that occurs in blood cells and affects the blood and bone marrow; in the community it is known as blood cancer.

Bone marrow produces blood cells. Leukemia can develop because of a problem with blood cell production. As a result, all types of this disease cause rapid and uncontrolled growth of abnormal bone marrow and various blood cells.

The types of blood cells are:

Who commonly develops leukemia?

Leukemia most commonly occurs in people aged 55 and older, and the average age at diagnosis is 66. It is also one of the most common cancer types in people younger than 20. Younger people have a greater likelihood of survival. Nevertheless, the chance of survival depends on various factors, including the person's age and response to treatment.

What are the types of leukemia?

There are many different types of leukemia. The main differences between the types are based on how quickly the disease progresses and the types of cells it affects.

The 4 main types of leukemia are:

1. Acute lymphoblastic leukemia (ALL)
2. Acute myeloid or myelogenous leukemia (AML)
3. Chronic lymphocytic leukemia (KLL)
4. Chronic myeloid or myelogenous leukemia (KML)

• You may be interested: What is the difference between leukemia and lymphoma?

What do acute and chronic leukemia mean?

A white blood cell passes through several stages during its lifetime.

Acute Leukemia: In acute leukemia, cells multiply rapidly and collect in the bone marrow and blood. They leave the bone marrow too early and are not functional.

Chronic Leukemia: It allows more mature and functional cells to be produced. In other words, it occurs when only some blood cells cannot function normally, and causes slower degeneration (deterioration).

Lymphocytic (lymphoblastic) and Myeloid Leukemias

What is lymphocytic leukemia?

It is a type of blood cancer in which the bone marrow produces too many lymphocytes (white blood cells) (for lymphocytes, see figure 1 above). A lymphocyte is a white blood cell that plays a role in the immune system.

What is myeloid leukemia?

It is a type of blood cancer in which there are too many myeloblasts (immature white blood cells that are not lymphoblasts) in the bone marrow and blood. 

According to the National Cancer Institute, approximately 1.5% of people in the United States will be diagnosed with leukemia at some point in their lives.

 

What is ALL (Acute Lymphoblastic Leukemia)?

ALL begins in the bone marrow, which produces stem cells that turn into red blood cells, white blood cells and platelets.

In a healthy person, the bone marrow does not release these cells before they are fully transformed. In people with ALL, however, the bone marrow releases white blood cells even though they have differentiated only slightly.

ALL is divided into 2 groups:

• B-cell ALL: It begins in B lymphocytes and is the most common form of ALL in children.
• T-cell ALL: It may cause enlargement of the thymus, a small organ opposite the windpipe, which can lead to breathing difficulties.

What causes Acute Lymphoblastic Leukemia?

According to research conducted in 2020, health experts still do not know the conditions that cause ALL. It is thought that it may occur because of genetic factors or exposure to the following:

• Exposure to benzene
• Ionizing radiation
• Certain viral infections
• Having received chemotherapy or radiotherapy

Although genetic factors are thought to play a role in ALL, ALL is not a familial disease or a hereditary cancer.

Who develops Acute Lymphoblastic Leukemia?

ALL (B-cell ALL) is the most common form of leukemia in children. The age group at greatest risk of developing this disease is children younger than 5. Its incidence also gradually increases after age 50.

What are the symptoms of ALL?

The symptoms of acute lymphoblastic leukemia are not specific to this disease and are therefore difficult to distinguish from those of other diseases. Nevertheless, the following can be listed as symptoms of ALL:

• Night sweats
• Easy injury
• Pale skin
• Swollen lymph nodes
• Enlarged testicles
• Weakness
• Unexplained weight loss
• Reduced urination
• Bone pain
• Changes in mood and thoughts
• Shortness of breath

What is AML (Acute Myeloid or Myelogenous Leukemia)?

In a person with acute myeloid leukemia, the bone marrow produces abnormal versions of platelets, red blood cells and white blood cells called myeloblasts.

It can occur in one of the following types of bone marrow cells:

• Myeloblasts: They usually form granulocytes, another type of white blood cell.
• Monoblasts: They usually turn into white blood cells called monocytes or macrophages.
• Erythroblasts: They turn into red blood cells.
• Megakaryoblasts: They usually turn into cells that form platelets.

Doctors also divide AML into subtypes according to the following:

• The type of bone marrow cell in which the cancer began and the maturity of the cells
• Whether the cells have chromosomal or genetic changes
• Whether the leukemia is related to previous cancer treatment
• Whether children with AML also have Down Syndrome

AML is a blood cancer that requires prompt medical intervention.

What causes Acute Myeloid Leukemia?

A type of blood cancer that prevents the body from producing enough healthy blood cells, myelodysplastic syndrome, is the most common risk factor for AML. Other risk factors are as follows:

• Aplastic anemia
• Down Syndrome
• Bloom Syndrome (a genetic condition)
• Exposure to radiation
• Exposure to tobacco smoke
• Exposure to benzene
• A history of chemotherapy

Who develops Acute Myeloid Leukemia?

The group most often affected by AML is people aged 45 and older. Although it is rare compared with other cancer types, it is one of the most common types of leukemia in adults. In children, it is the second most common type of leukemia.

What are the symptoms of AML?

Although the symptoms of Acute Myeloid Leukemia vary, the main symptoms of AML are:

• Easy injury
• Fatigue
• Frequent nosebleeds
• Frequent infections
• Fever
• Bleeding gums
• Unexpected weight loss
• Shortness of breath
• Bone pain

What is KLL (Chronic Lymphocytic Leukemia)?

In the United States and other Western countries, chronic lymphocytic leukemia is seen as the most common form of leukemia among adults.

In a person with chronic lymphocytic leukemia, the lymphocytes generally appear to be fully formed, but they are less able to fight infection than healthy white blood cells. Lymphocytes tend to develop very slowly, so a person may have had KLL for a long time before showing symptoms.

KLL is also divided into two subtypes:

• One progresses slowly and causes the body to have high levels of characteristic lymphocytes but only slightly low levels of healthy red blood cells, platelets and neutrophils.
• The other type progresses more rapidly and causes a significant decrease in the levels of all healthy blood cells.

What causes Chronic Lymphocytic Leukemia?

Genetic factors are the most likely cause. Other factors can be listed as follows:

• Exposure to radiation
• Tobacco use
• Exposure to benzene

Who develops Chronic Lymphocytic Leukemia?

Chronic lymphocytic leukemia is rare in children. It can generally develop in adults aged 70 and older. However, it can also affect a person as young as 30.

What are the symptoms of KLL?

There are generally no early symptoms of chronic lymphocytic leukemia. When symptoms appear, the following occur:

• A fever above 37 C lasting more than 2 weeks without signs of infection
• Night sweats without signs of infection
• Extreme fatigue
• Loss of appetite
• Unexpected weight loss
• Swollen lymph nodes (in 50-90% of KLL patients)

What is KML (Chronic Myeloid or Myelogenous Leukemia)?

Chronic myeloid leukemia is a slowly progressing type of leukemia that develops in the bone marrow. According to the American Cancer Society, a genetic change occurs in early forms of myeloid cells, ultimately resulting in KML cells. These leukemia cells then begin to grow, divide and enter the blood.

What causes Chronic Myeloid Leukemia?

Chronic myeloid leukemia results from a rearrangement of genetic material between chromosomes 9 and 22. This rearrangement combines, from chromosome 9, a fragment of the ABL1 gene with the Philadelphia chromosome, chromosome 22, which supplies the BCR gene. The product of this fusion (joining) is called BCR-ABL1.

The BCR-ABL1 complex produces a protein that promotes cell division and stops apoptosis, the process of cell death generally carried out to remove cells that are not needed or have been damaged. Cells continue to divide and do not destroy themselves, resulting in overproduction of abnormal cells and a lack of healthy blood cells.

Who develops Chronic Myeloid Leukemia?

Chronic myeloid leukemia generally occurs in adults. People aged 65 and older account for almost half of those diagnosed with KML.

What are the symptoms of KML?

Although the symptoms of KML are not entirely clear, they can be listed as follows:

• Weakness
• Fatigue
• Night sweats
• An early feeling of fullness
• Weight loss
• Fever
• Bone pain

How is leukemia treated?

Acute leukemia treatments

Acute leukemia treatments generally involve 3 main stages:

• Induction therapy
• Consolidation therapy
• Maintenance therapy

Induction therapy

The aim of this stage is to kill leukemia cells using chemotherapy to cause remission of the cancer. This stage of treatment lasts approximately 1 month.

The following drugs are most commonly used in induction therapy:

• Vincristin
• Deksametazon
• Prednizon
• Doksorubisin
• Daunorubisin

People receiving chemotherapy remain in close contact with the hemato-oncology team because of the risk of serious infection and complications.

Consolidation therapy

Even if treatments up to this stage have led to remission, cancer cells may be hiding in the body. Consolidation therapy is therefore necessary. This stage involves receiving high-dose chemotherapy. The treating doctor may also recommend targeted drugs or stem cell transplantation.

Maintenance therapy

This stage consists of successive chemotherapy treatments, and treatment can last between 6 months and 2 years.

In conclusion;

• Because ALL progresses rapidly, it requires prompt medical intervention. Approximately 80 – 90% of adults with ALL experience complete remission for a period during treatment, and most recover from the disease with treatment. Relapse is common in adults, so the overall cure rate is 40%. However, individual factors also play a role.
• The later the age at AML diagnosis, the more difficult treatment becomes. More than 25% of adults who achieve remission live for 3 years or longer after AML treatment.

Chronic leukemia treatments

Because KLL tends to progress slowly and treatment can have unwanted side effects, some people with this disease go through a period of careful monitoring and waiting before starting treatment.

For a person with KML, the focus is generally on providing the right treatment according to the disease's stage. To do this, the treating doctor assesses how quickly the leukemia cells are developing and the extent of the symptoms. Stem cell transplantation can be effective, but requires additional treatment.

If the only concern is an enlarged spleen or swollen lymph nodes, the person may receive radiotherapy or undergo surgery. If there are too many KML cells, the doctor may also recommend leukapheresis. This is effective only for a short time, but allows chemotherapy to begin working. For high-risk patients, doctors may recommend stem cell transplantation.

In conclusion;

• KML can be treated with stem cell transplantation. However, this treatment is very invasive (interventional) and is not suitable for most people with KML. The United Kingdom National Health Service estimates that 70% of men and 75% of women live for at least 5 years after a KML diagnosis. The earlier a person is diagnosed, the better the likelihood.

Life expectancy statistics for leukemia by age

The rate showing how many people remain alive 5 years after diagnosis is called 5-year survival. The latest data show that the 5-year overall survival rate for all leukemia types is 61.4%. This is, of course, a very general figure; life expectancy statistics vary according to leukemia subtypes and the other factors below. 

Factors affecting the survival rate;

• Age
• Time of diagnosis
• The cancer's progression and spread
• Type of leukemia
• Family history
• Extent of bone damage
• Exposure to certain chemicals
• Having received certain chemotherapy and radiation treatments
• Chromosomal mutations
• The body's response to treatment
• Blood cell count
• Tobacco use

According to the United States National Cancer Institute, death rates for all leukemias by age group:

One of the most important factors in leukemia treatment: Support

A leukemia diagnosis is a difficult, life-changing process for both the individual and their loved ones.

Although everyone reacts differently after a cancer diagnosis, it is very common to be left with complex emotions. Some remain brave to protect their loved ones, while others will openly seek support. It should be remembered that providing support applies to everyone.

• Support from the doctor: The doctor answering questions about the future, such as leukemia, its symptoms, treatment options, stages and survival rates, will help the person understand their situation.
• Support from friends and family: The person's friends and family can provide sincere and emotional support. They should also help with the very difficult situations the person may face daily because of leukemia symptoms or treatment.
• Support groups: These groups are helpful communities where advice drawn from experiences or support offered by experts is shared. They provide support both to leukemia patients and to their loved ones.
• Charitable organizations: Organizations such as the Leukemia and Lymphoma Association are dedicated to providing support to people diagnosed with cancer.

Summary

Leukemia, which has 4 basic types, is a cancer that affects the blood and bone marrow. The types differ according to the cells they affect and how quickly they progress. It can affect people of all ages. Treatments for all types of leukemia continue to develop to help people live longer and better with these conditions.

When should you see a doctor?

General symptoms may vary depending on the type of leukemia. People showing the following symptoms should consult a doctor:

• Fatigue
• Weakness
• Easy injury
• Pale skin
• Swollen lymph nodes
• Fever
• Chills
• More frequent and heavier menstrual cycles than usual
• Swollen and bleeding gums
• Dizziness
• Weight loss
• Night sweats
• Frequent infection
• Pain in bones and joints