Diagnosis of Blood Cancer

Executive Summary

Blood cancer is diagnosed based on signs and symptoms. There are different types of tests for the diagnosis of blood cancer. The blood test is the most common diagnostic approach for blood cancer. Complete blood count measures all the blood cells involving blood cells, red blood cells, platelets, hemoglobin, and hematocrit. Blood chemistry estimates the value of electrolytes, fats, proteins, glucose, and enzymes, which helps understand how the liver, kidney, and other organs function. The blood smear is done to check for any abnormalities. White cell differential is carried out for a complete blood count test. Different diagnostic approaches include FISH (Fluorescence in situ hybridization), flow cytometry, immunophenotyping, karyotype test, polymerase chain reaction, and infection screening. Bone marrow tests for blood cancer also involve bone marrow aspiration, bone marrow biopsy, and lymph node biopsy. Imaging tests include chest x-rays, computed tomography (CT) scan, magnetic resonance imaging (MRI) scan, ultrasound, and positron emission tomography (PET) scan. Spinal tap, urine test, and differential blood cancer diagnosis are other major diagnostic approaches for blood cancer.

Diagnostic Approach of Blood Cancer

Blood cancer has a lot of different types, so there are specific tests for different types of cancer. But if there are abnormalities found when you go for a standard checkup or a blood test for some other reason, further tests are ordered to diagnosis of blood cancer. Acute blood cancer show many symptoms and multiply, whereas chronic cancers take time to show symptoms, so they’re a little difficult to diagnose. There are different types of tests for the diagnosis of blood cancer. It’s always advisable to take a couple of tests to ensure what’s going on. 

Blood tests 

The origin of the disease is because of the abnormality of the DNA in the blood cells. So, a small amount of blood is taken for the veins and is tested for Complete blood count – This tests measures all the blood cells in your blood which helps in the diagnosis of blood cancer ^​1​, including the

• The white blood cells – These cells help fight infection in the body. There are five different types of white blood cells. A complete blood count test quantifies the number of white blood cells in the body, and an overall blood count with a differential test gives the accurate numbers of the five white blood cells.   
• The red blood cells – These cells aid in transporting the oxygen from the lungs to the rest of the body.  
• Platelets – These cells help clot the blood in the event of injury.
• Haemoglobin – This is a protein in the red blood cells that assists in carrying the oxygen from the lungs to the tissues and other organs. 
• Hematocrit – This assesses the number of Red blood cells in the blood. Having an alarmingly high and low number of RBCs in the blood can signify a problem. 

If the test finds disturbingly too many or too few blood cells, it’s a sign of a problem. Then the blood is sent to a specialist for a much clear look at the problem. 

Note: Complete blood count tests are also called CBC, total blood count and blood cell count.

Blood chemistry: This test measures substances like electrolytes, fats, proteins, glucose and enzymes, which helps understand how the liver, kidney and other organs function. Suppose a surprising change in the number of substances is a sign of a problem. This test helps to know the overall health and shows the problems.

Blood smear: When the doctor feels that the complete blood count test isn’t enough and finds the need for more tests, then they recommend the blood smear test. Many tests are computer analyzed, but the blood smear test is where the lab technician looks for the size, shape and number of the blood cells ( the red blood cells, the white blood cells and the platelets) and checks for abnormalities ^​2​. 

Note: the other names for blood smear tests are peripheral smear, peripheral blood film, smear, blood film, manual differential, differential slide, blood cell morphology, and blood smear analysis.

White cell differential: This test is frequently done as a part of a complete blood count test ^​3​. As the name suggests, it computes the white blood cells in the body, which is important because the primary function of the white blood cells is to fight infection. There are five different types of white blood cells: 

• Neutrophils – These cells help mainly in fighting off infections. They travel to the problem area and release enzymes to help fight off the infections. They can also communicate with other cells to help repair or give a proper immune response. Neutrophils are the more prevalent type of white blood cell.
• Lymphocytes – Lymphocytes have two types of cells, the B cells and the T cells. The B cells produce antibodies to help fight the infections of foreign bodies like viruses, bacteria and toxins. The T cells lockdown and knock down the body’s cells, infected with viruses, bacteria and cancer cells. 
• Monocytes – The primary function of monocytes is to eliminate dead and damaged cells. They also help the other white blood cells fire up the immune system to fight cancer cells. 
• Eosinophils – These white blood cells are essential in fighting parasitic infections, inflammatory processes and allergic reactions. Guarding the body against parasites and bacteria is also a necessary function of Eosinophils. 
• Basophils – These cells are often called the “immune surveillance”. It means that they can discover and dismantle the budding cancer cells. An additional purpose of this type of white blood cell is to release histamine in their granules to control Allergic reactions and Asthma attacks.

Note: Other names for the white cell differential test are Complete blood count (CBC) with differential, Differential, White blood cell differential count, and Leukocyte differential count. 

FISH (Fluorescence in situ hybridization) – This test charts the genetic material of a person’s cells. The test focuses on a small number of particular changes in genes or chromosomes in chronic Lymphocytic leukemia cells. It gives details on gene alterations in chromosomes, like informing which part is absent, lost or removed ^​4​. The outcome of this test will help the doctors to provide the essential treatment. 

Flow cytometry – is a technique to find blood cells through blood or a bone marrow sample. If the doctor’s initial tests show the excessive presence of white blood cells, then the flow cytometry test reveals that cancer is the cause. It exposes the form, size, computation and other characteristics of the white blood cells ^​5​. 

Immunophenotyping

This test helps to point out cells based on the indicators or antigens existing on the cell’s exterior, nucleus or cytoplasm. Immunophenotyping is widely used to differentiate: Acute Myeloid leukemia and Lymphoid leukemia, the B cell and T cell Lymphoid neoplasms, reactive and neoplastic expansions of lymphocytes ^​6​. It also helps in foreseeing prognostication in lymphoma and spotting lymphocyte subsets. The test has two methods based on the samples. If the example given is fluid suspensions, then the flow cytometry method is used, which determines cell lineage in lymphoma and leukemia. If the model shown is cells on slides, then the immunocytochemistry test method determines the cell lineage in tissues with suspected lymphoma.

Karyotype test

Our body cells have chromosomes that contain genes that are a part of DNA passed down from the parents to the offspring. The number of chromosomes found in an average human being is 46. If there are additional or fewer chromosomes, you possess a genetic disease. Kyrotype tests are generally used to find congenital abnormalities in a growing baby ^​7​. They are also used to determine whether an adult has any genetic disorders that can be passed on to their children. 

Note: Kyrotype tests are also called genetic testing, chromosome testing, chromosome studies and cytogenetic analysis.

Polymerase chain reaction

These tests are quick, accurate and can find the mutation in the early stages of the disease. These tests work by taking a sample of saliva, mucus, blood or tissue, and the DNA and RNA of the pathogens or abnormal cells are found. They can also determine how well the prescribed treatment works for the body. 

Note: other names for Polymerase chain reaction are PCR tests, rtPCR, reverse transcription PCR, qPCR, quantitative PCR, and real-time PCR.

Infection screening

This test checks whether the patient is infected with other diseases or viruses to be treated for both blood cancer and other diseases. 

Bone Marrow tests for diagnosis of blood cancer

The surface of the bone is the hard part of the bone, but the inside of the bone is a soft part called bone marrow which contains blood stem cells that become the red blood cells, white blood cells and platelets. Sometimes abnormalities or diseases are spotted in the bone marrow before being smeared in blood ^​8​. There are two types of bone marrow tests used to diagnose blood cancer. 

Bone marrow aspiration – a needle is used to take bone marrow fluid.

Bone marrow biopsy – a needle that takes a smidgin of bone marrow tissue, preferably from the hip area. 

These tests usually take about 30 minutes, and the samples are taken to the labs to check whether the blood stem cells are producing healthy blood cells or if there are any abnormalities in the cells. Bone marrow tests mainly diagnose leukaemia, multiple myeloma and lymphoma. 

Lymph node biopsy: Lymph nodes are tissues located in different body parts like the neck, chest, abdomen, armpit and groin. These tissues make white blood cells that fight infection. If cancer has spread to lymph nodes, it may trap cancer carrying cells. Lymph node biopsy withdraws a few tissues from lymph nodes and examines these tissues under the microscope. If the results show abnormally large lymph nodes, there are cancers in the body. 

Imaging tests

These tests are painless and use different forms of energy to take a pretty detailed image of the human body. These tests are not essential to diagnosing blood cancer because they don’t form tumours but help stage cancer. 

Chest X-rays

A chest X-ray and a bone X-ray are taken to check for abnormal enlargement of lymph nodes. 

Computed tomography (CT) scan

It is a series of X-rays taken from different angles to create a three-dimensional picture of the interior and body’s exterior. This test determines any enlargement in the lymph nodes, spots, organ abnormalities and tumours. 

Magnetic resonance imaging (MRI)scan

It does not involve radiation but uses magnetic and radio waves to give us a complete view of blood vessels, bones and organs. MRI shows changes in the bones that can diagnose cancers like myeloma and is also helpful in detecting leukaemia that affects the spinal cord and brain.

Ultrasound

The ultrasound gives us details about the size of the spleen. Suppose the test results show an increased spleen size, which means that the person has lymphoma. 

Positron emission tomography (PET) scan

Before the scan begins, a shot of radioactive sugar is injected into the body, taken up by metabolically active cells, which gives us information about the abnormal metabolic activity, if there’s any. It helps mainly in detecting chronic leukaemia and lymphoma. 

Spinal tap –

This test takes a sample of fluid from around the brain and spinal cord. The brain and spinal cord make up our central nervous system which coordinates everything. So this test determines mainly the tumours and diseases that affect the brain and spinal cord. This test is also known as lumbar puncture. 

Urine test –

The kidneys filter out proteins, blood cells, and other urine chemicals. The urine consists of all the abnormalities in the blood cells, which helps determine and find the disease. 

Differential diagnosis of blood cancer

There are some diseases whose symptoms are very similar to leukaemia. Some of them are 

• Aplastic anemia: This is a condition in which the blood stem cells of the bone marrow stop generating blood cells of all types. 
• All of the Myeloproliferative disorders – which cause abnormalities in blood cells that grow in the bone marrow, resemble leukemia.
• Myelodysplastic syndromes – originated in the bone marrow and are called pre-leukemia but most likely have chances of developing into Acute myeloid leukemia. 
• Viral infections – some viral diseases like HIV, Epstein – Barr virus, and cytomegalovirus can cause many lymphocytes.

References