Leukemia: Types, Symptoms, Causes, Risk factor, Diagnosis, staging, Treatment and Outlook


Leukemia can happen when there is a problem with the production of blood cells. It usually affects the leukocytes, or white blood cells. Leukemia refers to cancers of the WBCs.

May 6, 2018

Leukemia is a cancer of the blood or bone marrow. Bone marrow produces blood cells. Blood cells include red blood cells (RBCs), white blood cells (WBCs), and platelets.
Leukemia can happen when there is a problem with the production of blood cells. It usually affects the leukocytes, or white blood cells. Leukemia refers to cancers of the WBCs. WBCs are a vital part of your immune system. They are the potent infection fighters which protect your body from bacteria, viruses, and fungi, as well as from abnormal cells and other foreign substances. In leukemia, the WBCs divide too quickly and eventually crowd out normal cells which can not function properly.
WBCs are mostly produced in the bone marrow, but certain types of WBCs are also made in the lymph nodes, spleen, and thymus gland. Once formed, WBCs circulate throughout your body in your blood and lymph which is the fluid that circulates through the lymphatic system. It then concentrated in the lymph nodes and spleen.
Mostly it affect people over the age of 55 years, but it is also the most common cancer in children under 15 years. Acute leukemia develops quickly and worsens rapidly, but chronic leukemia gets worse over time.

Types of Leukemia:

Leukemia can be divided into four main groups which include acute, chronic, lymphocytic, and myelogenous leukemia.

Acute and Chronic Leukemia:

Leukemia can be acute or chronic (slow onset). In acute leukemia, cancer cells multiply quickly. The immature and useless cells develop rapidly and collect in the marrow and blood. They are squeezed out of the bone marrow too early and are not functional. In chronic leukemia, the disease progresses slowly and early symptoms may be very mild.

Lymphocytic and myelogenous leukemia:

Leukemia is also classified according to the type of cell. Leukemia involving myeloid cells is called myelogenous leukemia. Myeloid cells are immature blood cells that produce red blood cells, other types of white cells, and platelets which normally become granulocytes or monocytes. Leukemia involving lymphocytes is called lymphocytic leukemia. A lymphocyte is a kind of white blood cell that plays a role in the immune system.
There are four main types of leukemia:

Acute lymphocytic leukemia (ALL):

This is also known as acute lymphoblastic leukemia, which is the most common type of leukemia among young children. It can also affect adults, especially after the age of 65 years. The subtypes of ALL are:

  • precursor B acute lymphoblastic leukemia
  • precursor T acute lymphoblastic leukemia
  • Burkitt's leukemia
  • acute biphenotypic leukemia

Chronic lymphocytic leukemia (CLL):

This is most common among adults over 55 years, but it can also affect younger adults. It is the most common type of leukemia in adults, and it rarely affects children. It is more common in men than in women.

Acute myelogenous leukemia (AML):

AML is more common in adults than in children which develops quickly. It affects men more often than women. Symptoms of AML include fever, difficulty breathing, and pain in the joints. Environmental factors can trigger it. Chemotherapy is the main treatment. Sometimes, a bone marrow transplant may be recommended.

Chronic myelogenous leukemia (CML):

CML mostly affects adults. Cancer therapy, called Gleevec, or imatinib are used in this type of leukemia. Many people with CML have a gene mutation that responds to these therapies.

Symptoms of Leukemia:

Depending on the type, symptoms of Leukemia may vary. These include:

Poor blood clotting:

Blood clotting is crucial when immature white blood cells crowd out platelets. This can cause easy bleeding or bruising and slow healing. A minor hemorrhage may also develop which looks like small red to purple spots on the body.

Frequent infections:

As the white blood cells are suppressed or not working properly, they can not fight off infection resulting in frequent infections. The immune system may attack other good cells of the body.

Anemia:

Anemia can occur as a result of shortage of good red blood cells. This can involve difficult breathing and pale skin.

Other symptoms:

Nausea, fever, chills, night sweats, flu-like symptoms, weight loss, bone pain or tenderness, persistent fatigue, tiredness and recurrent nosebleeds are some of the most common symptoms which resembles other illnesses. If the liver or spleen becomes enlarged the person may feel full and will eat less, resulting in weight loss.
Weight loss can also occur even without an enlarged liver or spleen. Headache may indicate that the cancerous cells have invaded the central nervous system (CNS).
As most of the symptoms may resemble symptoms of the flu and other common illnesses, tests are needed to confirm a diagnosis of leukemia.

Causes of Leukemia:

When the DNA of immature blood cells, mainly white cells, becomes damaged  because of certain abnormalities they get multiplied. The blood cells grow and divide continuously, increasing in numbers. Healthy blood cells die after a while and are replaced by new cells, which are produced in the bone marrow. The abnormal blood cells do not die, there by accumulated, occupying more space.
As more cancer cells are produced, they stop the healthy white blood cells from growing and functioning normally, by crowding out space in the blood causing Leukemia.

Risk factors:

Factors that may increase the risk of developing leukemia include:

Previous cancer treatment:

People who have had certain types of chemotherapy and radiation therapy for other cancers have an increased risk of developing certain types of leukemia.

Genetic disorders:

Genetic abnormalities seem to play a role in the development of leukemia. Down syndrome is a genetic disorders, which is associated with an increased risk of leukemia possibly due to certain chromosomal changes.

Exposure to certain chemicals:

Exposure to certain chemicals can have an increased risk of some kinds of leukemia. Example include benzene, which is found in gasoline and is used by the chemical industry.

Smoking:

Smoking cigarettes increases the risk of acute myelogenous leukemia.

Family history of leukemia:

Your risk of the disease may be increased if members of your family have been diagnosed with leukemia.

Viruses:

Certain virus such as the human T-lymphotropic virus (HTLV-1) and HIV is a known risk factor for causing leukemia. People with known risk factors does not necessarily get leukemia. However, many people with leukemia have none of these risk factors.

Diagnosis of Leukemia:

Based on complete history and physical examination, your doctor will start the diagnosis of the disease. Physical signs of leukemia, such as pale skin from anemia, swelling of your lymph nodes, and enlargement of your liver and spleen are checked in physical examination. But leukemia can't be fully diagnosed by a physical examination. Therefore blood tests, biopsies, and imaging tests are also done to make a diagnosis.
Abnormal appearance of red or white blood cells or platelets can be detected through blood test. A complete blood count determines the numbers of RBCs, WBCs, and platelets in the blood. A bone marrow test may be recommended in which a sample of bone marrow from your hipbone is removed. The bone marrow is removed using a long, thin needle. The sample is then sent to a laboratory to look for leukemia cells. Specialized tests of your leukemia cells may reveal the type of leukemia and its growth rate that are used to determine your treatment options. Biopsies of other organs such as the liver and spleen can show if the cancer has spread.
A number of other tests can be used to assess the progression of the disease. These include:

  • Flow cytometry examines the DNA of the cancer cells and determines their growth rate.
  • Liver function tests show whether leukemia cells are affecting or invading the liver.
  • Lumbar puncture is performed to determine if the cancer has spread to the central nervous system. This can be performed by inserting a thin needle between the vertebrae of your lower back to collect spinal fluid.
  • Imaging tests, such as X-rays, ultrasounds, and CT scans, help doctors look for any damage to other organs that is caused by the leukemia.

Staging of Leukemia:

Staging can be done once leukemia is diagnosed which helps your doctor determine your treatment plan. Based on how cancer cells look under the microscope and the type of cell involved, Leukemia can be staged as AML and ALL.
ALL and CLL are staged based on the WBC count at the time of diagnosis. Staging of AML and CML can be done based on the presence of immature white blood cells, or myeloblasts, in the blood and bone marrow.

Treatment of Leukemia:

Based on your age and overall health, the type of leukemia you have, and whether it has spread to other parts of your body, including the central nervous system, leukemia treatment options will be decided by your doctor. Leukemia is usually treated by a hematologist-oncologist, who specialize in blood disorders and cancer. Leukemia can be fatal, but several treatment options are available for treating and controlling the disease and its symptoms.
Common treatment options include:

Chemotherapy:

This is the most common form of treatment for leukemia. The procedure uses drugs to kill leukemia cells. Depending on the type of leukemia, you may have to take either a single drug or a combination of different drugs.These drugs may come in a pill form, or they may be injected directly into a vein.

Radiation therapy:

This therapy uses high-energy radiation to damage leukemia cells and inhibit their growth. You lie on a table while a large machine moves around you during radiation therapy. The radiation is directed to precise points on your body where there is a collection of leukemia cells. Radiation can be applied to a specific area or to your entire body. Radiation therapy may be used to prepare for a stem cell transplant.

Stem cell transplant:

This procedure is also called a bone marrow transplant. It is a procedure to replace your diseased bone marrow with healthy bone marrow. You will receive high doses of chemotherapy or radiation therapy to destroy your diseased bone marrow before a stem cell transplant. Then you receive an infusion of blood-forming stem cells that help to rebuild your bone marrow. You may receive stem cells from a donor called allologous transplantation, or in some cases you may be able to use your own stem cells called autologous transplantation.

Biological or Immune therapy:

This therapy uses treatments that help your immune system recognize and attack cancer cells.

Targeted therapy:

Targeted therapy uses drugs that attack specific vulnerabilities within your cancer cells.
For example, the drug imatinib (Gleevec) stops the action of a protein within the leukemia cells of people with chronic myelogenous leukemia. This can help control the disease.

Outlook of Leukemia:

The outlook for people who have leukemia depends on the type of cancer they have and their stage at diagnosis.The sooner leukemia is diagnosed and the faster it is treated, the better the chance of recovery. Some factors, like older age, past history of blood disorders, and chromosome mutations, can negatively affect the outlook.
Regular monitoring, including blood tests and possible bone marrow tests should be done for patients who experience remission to ensure the cancer has not returned. Over time, the frequency of the tests can be reduced if the leukemia does not return.