The different tests required for detecting blood-cancer

August 09 11:15 2023 Print This Article

Introduction

Blood cancer is a serious condition which shows prominent symptoms in some people and muted symptoms in some others. Once the person feels suspicious of his/her health, or symptoms, and approaches a doctor, the latter will conduct a battery of tests to confirm or rule out blood-cancer. These tests, across the different types of blood cancer, are as follows:

1. Physical Examination

The doctor will look for swollen lymph nodes in the neck, underarms, groin and certain other parts of the body, as well as an enlarged liver or an enlarged spleen. He/she will also examine the skin for scaly patches, pink or red rashes, round bumps, and tiny red dots. He/she will also look for bleeding gums and unusual bruising.

2. Blood Tests

• Complete blood count (CBC): This test will determine the number of RBCs, WBCs and measures certain components in the person’s blood. If the quantities are too low or too high for any of the components, it requires further examination.
• Blood smear: The above CBC test has its own limitations. So, the doctor may ask for this test which shows whether the blood-cells look normal or not, and then if their quantities are right.
• Blood chemistry: Another standard test that measures levels of blood-sugar, proteins, cholesterol, electrolytes, and some other compounds dissolved in blood. This will indicate if everything is normal or something doesn’t look right.
• White cell differential: This shows the number of each type of WBC in the blood. This can indicate the presence of certain blood-cancer types such as leukaemia, and at what stage the condition is in.
• FISH (fluorescence in situ hybridization): This focuses specifically on the blood-cancer cells. The test will determine how fast their genetic blueprint is changing. This will indicate how quickly the disease is progressing which helps decide the right treatment.
• Flow cytometry: This can identify the types of cells in the blood or bone marrow. Parameters covered include – the number of white blood cells, their size and shape.
• Immunophenotyping: This test can tell the difference between the types of cancer cells. It looks for the presence or absence of certain protein markers on the surface of blood-cells.
• Karyotype test: This test looks for changes in number, shape, size and arrangement of chromosomes in the blood-cells or bone-marrow cells. That can indicate the direction in which the condition is progressing and decide the course of treatment.
• Polymerase chain reaction (PCR): Like with any other type of cancer, blood cancer too has its own markers. These are certain proteins or enzymes present in the blood when certain cancers exist. For example, levels of an enzyme called lactate dehydrogenase (LDH) may indicate the presence of lymphoma. A PCR test will catch or detect all such markers which other tests may miss.

3. Biopsies

• Biopsy of the Bone marrow: Bone marrow is the central, spongy tissue in the bones where RBCs and WBCs are generated. The presence of abnormal cells in the bone marrow can indicate blood-cancer. The biopsy is of two types. In aspiration method, a long thin needle is used to extract a small sample of the fluid in the bone marrow for examination under a microscope. In the 2nd method, a long and thicker needle is used to core out some of the solid material in the bone marrow, for examination under a microscope. In both the cases, the hip-bone is preferred. The patient is given local anaesthesia to minimize pain and discomfort.
• Biopsy of a Lymph Node: A part of, or an entire lymph node is removed and the same examined under a microscope. This can reveal the presence of abnormal lymphocytes, which is an indication of lymphoma.

4. Imaging Tests

• Chest X-ray: This can detect the presence of a tumour that has metastasized from blood-cancer in the chest region, infections, or a swollen lymph node.
• CT scan: This can help detect swollen lymph nodes, enlarged liver, enlarged spleen, and cancer that has metastasized into the heart, lung, brain or spinal-cord. For people who have already undergone or undergoing treatment for blood-cancer, the CT scan can show the outcome of treatment.
• MRI scan: This creates detailed images of the bones, internal organs, blood vessels and the lymphatic system. This helps detect the presence of tumours in any of these tissues.
• PET scan: This test uses a shot of radioactive isotope injected into the patient to show the person’s metabolism at work. This can help detect lymphoma and certain other cancers.

5. Genetic Test

Since cancer is caused by genetic mutations or changes in the DNA code, by examining the cancer cells and more specifically the genes or chromosomes in them, under a microscope, the doctors can determine the type of blood-cancer. FISH and Karyotyping tests described earlier are some examples of genetic tests. Other genetic tests include molecular testing, molecular genetics and cytogenetic testing.

6. Spinal Tap

If the blood-cancer has metastasized into the brain and spinal-cord, then the fluid around the brain or spinal cord will have some blood-cancer cells. This can be confirmed by extracting a sample of this fluid and examining under a microscope. To do so, the patient is made to lie on his/her side after which the back is made numb using numbing agents. Then a fine needle is inserted into the skin and all the way into the space between bones of the spine. A small sample of the fluid here is then extracted, the needle pulled out, and the wound on the skin is sutured.

7. Urine Test

When there is any cancer in the body, there are various proteins or enzymes released into the blood which act as markers of that cancer. Further, various bodily functions or processes are affected by the presence of a cancer. Then there is the immune system which is carrying on its own battle against the cancer cells. The sum total of all this is that there are a whole new lot of chemicals in the body compared to that of a healthy person, or one who does not have cancer. The kidneys excrete or throw these chemicals out of the body through the urine. So, a urine test will show up many of these chemicals which makes it easy to confirm or rule out blood-cancer.

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