Leukemia: Types, Symptoms, Causes, Risks, Diagnosis, Treatment and Outlook

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Illustration of leukemia

1Overview

The blood performs various roles in the body. Aside from carrying oxygen and nutrients to the various parts of the body, it helps in the fast response of the immune system.
Most adults have approximately five liters of blood.

The heart plays pivotal roles in the body – carry oxygen and nutrients to the cells and tissues, aid in removing waste, deliver immune cells to the affected area, transport hormones and other signals in the body, and regulate the core body temperature and pH levels.

The blood comprises the plasma, which makes up about half of the blood and the different cells including the red blood cells, white blood cells, and platelets. The red blood cells are responsible for transporting nutrients and oxygen to the various tissues in the body.
The white blood cells fight infections and the platelets help the blood to clot.

Leukemia is a type of cancer affecting the body’s blood-forming tissues, including the lymphatic system and the bone marrow. People with leukemia may have problems with their bone marrows. Usually, the bone marrow starts to produce abnormal white blood cells that do not work like normal ones. They grow faster and don’t stop growing when they should.

In time, these leukemia cells take over normal cells, leading to various complications such as infections, bleeding, and anemia.

The  Leukemia and Lymphoma Society reports that about one person in the United States is diagnosed with blood cancer every 3 minutes. In 2017, an estimated total of 172,910 people in the United States is expected to be diagnosed with leukemia, myeloma or lymphoma.

For leukemia, specifically, there were approximately 387,728 people living with leukemia in the United States in 2014. About 1.5 percent of both men and women will be diagnosed with leukemia in their lifetime, according to the 2012 to 2014 data.

2Types of Leukemia

Chronic Lymphocytic Leukemia (CLL)

This type of leukemia is the most common chronic leukemia in adults. People may not feel any symptoms for years.

Chronic Myelogenous Leukemia (CML)

This type of leukemia affects adults. This is a chronic condition wherein the person affected may go on without any symptoms, before entering the stage in which the cancer cells grow rapidly.

Acute Myelogenous Leukemia (AML)

Also called acute myelocytic leukemia, acute granulocytic leukemia, and acute
non-lymphocytic leukemia, this condition is found older people.

Acute Lymphocytic Leukemia (ALL)

ALL is a type of leukemia starts in the bone marrow where the blood cells are produced. Children are affected more than adults.

Other Types

The other kinds of leukemia include hairy-cell leukemia and acute promyelocytic leukemia.

3Symptoms

The symptoms of leukemia may differ, according to the type a patient has.
However, the most common symptoms of leukemia include:

  • Fever
  • Chills
  • Frequent infections
  • Easy bleeding
  • Easy bruising
  • Recurrent nose bleeding
  • Persistent weakness
  • Enlarged liver, spleen and inflamed lymph nodes
  • Unexplained weight loss
  • Petechiae or tiny red spots on the skin
  • Night sweating
  • Bone pain

4Causes

The exact cause is still unclear. However, many studies have linked the development of leukemia to environmental and genetic factors. Just like any other cancer types,
the uncontrolled growth and replication of cancer cells are seen as the culprits in cancer.

Leukemia forms when the blood cells undergo mutations in the body’s DNA. One of the major changes that happen in the DNA is chromosome translocation. In the process, a part of one chromosome breaks off and goes to a different chromosome. One type of translocation seen in patients with leukemia is an exchange of DNA between the chromosomes 22 and 9. This produces an oncogene, which is a cancer-promoting gene, called BCR-ABL.

As a result, the normal cells become cancerous, and they grow rapidly. They can also take over normal and healthy cells, leading to crowding out of the healthy blood cells in the bone marrow. The bone marrow may create fewer healthy red blood cells, white blood cells, and platelets, leading to the various clinical manifestations.

Leukemia is classified into two – acute and chronic. Acute leukemia is fast-growing and the symptoms appear quickly. On the other hand, chronic leukemia is slow-growing that gets worse steadily over time.

5Risk Factors

High levels of radiation

Individuals who are exposed to high levels of radiation are more likely to develop leukemia. Extremely high radiation exposure are those caused by nuclear or atomic bomb explosions, like that in Japan during the World War II. Nuclear power plant accidents are also considered hazardous such as the Chernobyl incident in 1986.

On the other hand, diagnostic tests used in the field of medicine that uses radiation are not that risky since these only use low levels of radiation.

Previous cancer treatment

People who underwent various cancer treatments like chemotherapy and radiation therapy for another type of cancer have a raised risk of developing some other types of cancers.

Working with certain chemicals

Exposure to high levels of benzene in the workplace may lead to an increased risk of leukemia. This chemical is widely used. Moreover, formaldehyde has also been linked to leukemia.

Genetic disorders

Some genetic disorders, particularly those causing abnormalities in the chromosomes, are linked to a heightened risk of leukemia. One of the most affected individuals is those with Down syndrome.

Smoking

Smoking cigarettes have been linked to an increased risk of leukemia. Cigarettes contain dozens of cancer-causing chemicals. In fact, studies have estimated that about 20 percent of AML cases were associated with smoking.

Family history

Individuals who are related to a first-degree relative who has CLL are at risk of the same type of leukemia. These include immediate family members such as parents, children or siblings.

Human T-cell leukemia virus (HTLV-1)

This virus causes a rare type of leukemia, particularly chronic lymphocytic leukemia.
The condition is called human T-cell leukemia. However, despite being caused by a virus, leukemia isn’t contagious.

Myelodysplastic syndrome

Some individuals with this blood illness are at an increased risk of developing acute myeloid leukemia.

6Diagnosis

The acute types of leukemia may be diagnosed immediately because of the symptoms the patient is feeling. On the other hand, the chronic types are usually incidentally found in a routine blood test, even before the symptoms begin.

To confirm a diagnosis, the doctor will conduct the following tests:

Physical examination and medical history

The doctor will assess for physical signs of leukemia such as swollen lymph nodes, enlargement of the spleen and liver or pale skin because of anemia. He will also interview the patient’s medical and personal history.

Blood tests

Usually, a complete blood count (CBC) and a blood chemistry are usually requested for the doctor to look at the levels of the blood cells. A peripheral blood smear can also determine the abnormalities in the various blood components.

Bone marrow aspiration and biopsy

These tests help determine the number of immature cells or blasts in the bone marrow. The tests can help reveal the other features and condition of the leukemia cells. A bone marrow aspiration is done by inserting a hollow needle into the hip bone to remove a small piece of bone marrow. The specimen is then examined under a microscope.

Other tests

Doctors can sometimes use imaging tests like ultrasound, CT scan, MRI, PET scan or chest x-rays to determine if the leukemia cells have affected the bones and other organs in the body such as the kidneys, lymph nodes, and the brain.

7Treatment

The goal of treatment for leukemia is to kill the cancer cells and allow normal cells to form in the bone marrow. The treatment options also depend on the type of leukemia, general health, and age.

Chemotherapy

the most common treatment option used for leukemia is chemotherapy. This is a treatment wherein chemicals are used to kill cancer cells. The side effects of this treatment include nausea, vomiting, weakened immune system, fatigue, and weakness.

Depending on the type of leukemia the patient has, chemotherapy may have a single drug or a combination of medicines.

Radiation therapy

Radiation therapy is a treatment option where high-energy beams are used to damage or kill leukemia cells. The treatment may be directed to a specific area in the body or the whole body.

Biological therapy

In this type of treatment, the immune system is triggered to recognize and kill the cancer cells.

Stem cell transplant

This procedure entails the replacement of the diseased bone marrow with a healthy one. Patients who will undergo stem cell transplant need to receive increased doses of radiation therapy or chemotherapy to damage or destroy the diseased bone marrow.

Targeted therapy

Targeted therapy uses medications that attack certain susceptibilities in the cancer cells. For instance, a drug is used to stop the action of a protein within the leukemia cells of individuals with CML.

Surgery

Sometimes, for people with inflamed and damaged spleen, surgery may be recommended to remove the organ.

8Outlook

Individuals with acute myelogenous leukemia (AML) may ask the doctor about their prognosis. The survival rate greatly depends on many factors like the patient’s medical history, the type of cancer, characteristics of cancer, stage of cancer, treatments opted and response to the treatment.