Lets proceed the series that we have started where we have been sharing various types of leukemia and their symptoms, signs, outlook, success rate, survival rate, risk factors, diagnosis, and treatment. Let’s move on to another type of leukemia, in fact it is the type of acute leukemia which is known as acute myeloid leukemia.
What is acute myeloid leukemia?
It is also known as acute Myelogenous leukemia and acute nonlymphocytic leukemia (ANLL). It is caused due to increased number of white blood cells called leukocytes that accumulate in the bone marrow and hinder the proper functioning of red blood cells and platelets. It is caused due to abnormal myeloid in blood cells making these cells cancerous. 2 % of cancer deaths occur due to acute myeloid leukemia. It is commonly seen in adults and is rarely occurring disease. In this type of leukemia, while blood cells increase in their number quickly and rapidly and condition gets worst if kept untreated for weeks or months.
Subtypes of acute myeloid leukemia:
|M0||acute myeloblastic leukemia minimally differentiated||–||5 %|
|M1||acute myeloblastic leukemia without maturation||–||15 %|
|M2||acute myeloblastic leukemia with granulocytic maturation||t(8;21)(q22;q22), t(6;9)||25 %|
|M3||Promyelocytic or acute promyelocytic leukemia (APL)||t(15;17)||10 %|
|M4||acute myelomonocytic leukemia||inv(16)(p13q22), del(16q)||20 %|
|M4 eo||myelomonocytic together with bone marrow eosinophilia||inv(16), t(16;16)||5 %|
|M5||acute monoblastic leukemia (M5a) or acute monocytic leukemia (M5b)||del (11q), t(9;11), t(11;19)||10 %|
|M6||acute erythroid leukemias, including erythroleukemia (M6a) and very rare pure erythroid leukemia (M6b)||–||5 %|
|M7||acute megakaryoblastic leukemia||t(1;22)||5 %|
Causes of acute myeloid leukemia:
All the causes of this disease are still unknown but there are certain risk factors that have been identified, avoiding and reducing these risk factors, chances of developing acute myeloid leukemia can be minimized. Some causes that have been identified are written down below:
- Chromosomal abnormalities.
- Mutation in DNA.
- Genetics or family history.
- Replacement of normal cells by leukemic cells.
- Increased number of white blood cells (leukocytes).
Symptoms of acute myeloid leukemia:
There are some symptoms that are associated with acute myeloid leukemia; These symptoms may be observed along with some other indications. If all or some of the symptoms are observed, immediately see your doctor. These symptoms are listed down below,
- Shortness of breath.
- Easy bruising.
- Inflammation in skin.
- Enlargement of spleen.
- Swelling of lymph nodes.
- Persistent or frequent infections.
- Pain in bones and joints.
- Bleeding gums.
- Bleeding nose.
- Spots on skin.
- Enlarged lymph nodes.
- Problem in blood clotting.
- Lack of balance.
- Blurred vision.
- Facial numbness.
- Slurred speech.
- Night sweats.
- Cold feeling.
- Weight loss.
- Loss of appetite.
Risk factors of acute myeloid leukemia:
Risk factors must be avoided to keep yourself save from acute myeloid leukemia. Risk factors associated with acute myeloid leukemia are listed down below:
- Genetics or family history.
- Age: Its risk increases with age,
- Sex: Men are more likely to suffer from this disease.
- Blood disorders.
- Exposure to chemicals.
- Exposure to harmful radiations.
- History of blood disorders.
- Chemotherapy drugs.
Diagnoses of acute myeloid leukemia:
When symptoms for acute myeloid leukemia are observed, they are reported to doctor, doctor then diagnose the disease by different types of tests.
It is diagnosed by following ways:
- Medical history
- Physical examination.
- Blood tests
- Complete blood count.
- Blood chemistry and coagulation tests.
- Routine microscopic test.
- Bone marrow tests.
- Bone marrow biopsy.
- Bone marrow aspiration.
- Flow cytometry.
- Fluorescent in situ hybridization (FISH).
- Polymerase chain reaction (PCR)
- Imaging tests.
- X ray.
- CT scan.
If some or all of the symptoms are observed in the patient, doctor will check for your medical history. As in risks and causes of leukemia we have seen that if you have some medical history of some other type of cancer and you got chemotherapy done as treatment of that cancer then they might be the causes of your getting suffer from acute myeloid leukemia. Moreover he will also ask you questions like how long these symptoms have been observed. He will ask for the risk factors as well.
In physical examination, doctor will look deeply in to your mouth, eyes. skin, spleen, liver and gums to check whether there is some infection or wound. Do they bleed?
He will get your test done to check the cause of infection or bleeding. If it is proved that these symptoms are due to leukemia then he will refer you to a doctor called hematologist, a doctor who has specialized in diseases and disorders of blood. Who will carry out your further tests and examination after diagnosis he will start your treatment.
The tests that he will carry out to diagnose acute myeloid leukemia are explained below:
Many blood tests are conducted to check various aspects of blood and blood cells. Following are the blood tests that are carried out for diagnosis.
Complete blood count:
We have established the fact earlier that, leukemia is caused due to increase in count of white blood cells or leukocytes occur beyond the normal level which are abnormal cells. Therefore in order to diagnose acute myeloid leukemia, complete blood count (CBC) will be carried out. If white blood count is within the range of 4000 to 11000 then the patient has not developed leukemia, otherwise if white blood cells count is greater than 11000 per milliliter, patient will be suffering from leukemia. In this test, blood samples are taken from vein.
Blood chemistry and coagulation tests:
Tests measure the amounts of chemicals in the blood and blood clotting ability. These tests also examine liver and kidney, if in reports some problems are detected then they might be due to leukemia. Patient is further subjected to more tests to check for the evidence of acute myeloid leukemia.
Routine microscopic test:
In routine microscopic exam, sample of blood, bone marrow, or CSF are examined under a microscope by a pathologist ( doctor specializing in lab tests) and might be reviewed by the hematologist/oncologist (a doctor specializing in cancer and blood diseases).The doctors will examine the size, shape, and other characteristics of the white blood cells to classify them into specific types.
Bone marrow tests:
Bone marrow aspiration:
Our bone marrow contains two types of substances one are solid tissues other is the liquid fluid. In bone marrow aspiration tissues from bone marrow are extracted and examined. Presence of immature cells in the bone marrow which are called as blasts is the indication that leukemia is acute rather than chronic.
Bone marrow biopsy:
Having said that bone marrow consists of two types of substances. The solid tissues which are examine in bone marrow aspiration. The other liquid fluid part is examined in bone marrow aspiration.
In this test, cells are exposed to chemical stains that react with only some specific types of leukemia cells. These stains result in color changes that can be observed by looking under a microscope, it helps the doctor to determine what type of cells are present. A stain can help distinguish between AML cells and acute lymphocytic leukemia (ALL) cells. The stain makes the granules of most AML cells to appear as black spots under the microscope, and it does not makes ALL cells to change colors.
In this test, cells from the blood or bone marrow samples are treated with special antibodies. Certain types of cells change color that can be observed under the microscope.
Flow cytometry: In flow cytometry which is a laser-based is used to examine count of blood cells, cell sorting, biomarker detection and protein, by suspending cells in a stream of fluid and passing them by an electronic detection system.
Fluorescent in situ hybridization (FISH):
Fluorescent in situ hybridization uses fluorescently labeled DNA probes to locate specific sequences of interest and identifies structural and numeric chromosomal changes including balanced rearrangements and micro deletions.
In this test, chromosomes are looked at under the microscope to check is there any mutation.
Polymerase chain reaction (PCR):
This test is used to check the BCR-ABLoncogene in leukemia cells. It is done on blood or bone marrow samples. It detects very small amounts of BCR-ABL, even if doctors can’t find the Philadelphia chromosome in then bone marrow cells with cytogenetic testing. Polymerase chain reaction (PCR) is used in the diagnoses of CML and it is also useful after treatment to see if copies of the BCR-ABL gene are still present. If copies of this gene are still present it is the indication that the leukemia is still present.
X ray: Chest X-ray will examine any disorder in the region of chest.
CT scan: It is a special kind of x ray in which beam is passed through body that gets the inner picture of body. This helps in checking for swollen lymph nodes.
MRI: Magnetic resonance imaging is used to check brain and spinal cord. It is done by radio and magnetic rays instead of x rays.
Ultrasound: Ultrasound makes use of sound waves and their echoes to make picture of internal organs. In this test a small microphone-like instrument called a transducer is placed on the skin which is first lubricated with a gel. It gives off sound waves and picks up the echoes as they bounce back from the organs. The echoes are then converted by a computer into an image that is displayed on a computer screen.
Ultrasound is used to look at lymph nodes to check whether they are swollen or not, moreover it also checks for enlarged liver or spleen.
Treatment of acute myeloid leukemia:
Acute myeloid leukemia patient is put on the following treatments and therapies.
- Remission induction therapy.
- Hematopoietic stem cell transplant.
- Drug therapy.
Remission induction therapy:
Remission induction therapy aims to kill leukemia cells in the blood and bone marrow. However it does not kill all the leukemia cells , therefore patient needs to get his further treatment done.
Consolidation therapy is also called post remission therapy. Purpose of this phase of treatment is to kill and wipe out the remaining leukemia cells. It decreases the risk of relapse.
Following therapies are included in this phase.
Chemotherapy: It is the form of remission induction therapy. It is also used for consolidation therapy. Chemotherapy makes use of chemicals to kill cancerous cells in the body. Patients who are suffering from AML stay in the hospital during chemotherapy treatments because the drugs destroy many normal blood cells in the process of killing leukemia cells. If the first cycle of chemotherapy does not results in remission, it is repeated.
Drug therapy: Arsenic trioxide (Trisenox) and all-trans retinoic acid (ATRA) are anti-cancer drugs and they can be used alone or along with chemotherapy for remission induction of a certain subtype of AML called promyelocytic leukemia. These drugs cause the leukemia cells which have a specific gene mutation to mature and die, or cause them to stop dividing.
Stem cell transplant:
In stem cell transplant, which is also called bone marrow transplant, consolidation therapy is done. Stem cell transplant helps re establish healthy stem cells by replacing unhealthy bone marrow with leukemia-free stem cells donated by a healthy donor, that regenerate healthy bone marrow. Before stem cell transplant, patient receives very high dose of chemotherapy or radiation therapy so that it can destroy leukemia-producing bone marrow. After that, patient receives infusions of stem cells from a compatible donor.
Success rate of acute myeloid leukemia:
2 out of 3 acute people who are suffering from acute myeloid leukemia (AML) that get standard induction chemotherapy (chemo) with daunorubicin and cytarabine go into remission. This means to say that the bone marrow has less than 5% blast cells, the blood cell counts are within normal limits, and there are no symptoms of the disease acute myeloid leukemia. The exact chance of remission depends on person’s specific prognostic factors, such as his age or the presence of certain gene or chromosome mutations.
Survival rate of acute myeloid leukemia:
Survival rate of people suffering from acute myeloid leukemia among different age groups is follow:
- Children having age 14 or less than 14 years have survival rate of 66 % .They survive 5 years or more after the diagnosis of the disease.
- People with age between 15 and 24 have success rate of 60 %. They survive 5 years or more after the diagnosis of the disease.
- People with age between 25 and 64 have success rate of 40 %. They survive 5 years or more after the diagnosis of the disease.
- People who have age greater than 56 years have success rate of 5 %. They survive 5 years or more after the diagnosis of the disease.
Survival rate for children has greatly increased. In 1960’c survival rate was 10 % which is now increased up to 66 %. Chances of recovery and survival are greatly increased in children as compare to any other age group, the reason behind this fact is that they have better ability to cope with and bear the intense therapies and treatments.
Statistics of acute myeloid leukemia:
According to American cancer society statistics:
- Almost 20,830 new cases of acute myeloid leukemia (AML) are identified each year. Mostly they are identified in adults.
- Almost 10,460 deaths occur from acute myeloid leukemia each year. Almost all these deaths occur in adults.