Can Cancer Be Detected in Blood Tests?

Reviewed on 5/4/2021

Blood and genomic tests

When a person is suspected to have cancer, doctors may perform a variety of tests to help diagnose cancer.
When a person is suspected to have cancer, doctors may perform a variety of tests to help diagnose cancer.

When a person is suspected to have cancer, doctors may perform a variety of tests to help diagnose cancer. Different types of blood tests are done to check for abnormal cells, cancer cells, proteins, tumor markers, or other substances made by the cancer cells. This helps determine if a person has cancer or any precancerous condition. Blood tests may also indicate if other organs of the body have been affected by cancer. Except for blood cancers, blood tests alone cannot diagnose cancer. However, they can give clues about the health condition of the body. Along with blood tests additional tests may be required to accurately diagnose cancer.

Blood tests

Different types of blood tests used to diagnose cancer include

Complete blood count (CBC)

A CBC test measures the size, number, and maturity of different types of blood cells found in the blood. It measures the number of red blood cells, white blood cells (neutrophils, eosinophils, basophils, monocytes, and lymphocytes), and platelets in the blood. This test also measures levels of hemoglobin and hematocrit in the blood. Blood cancer may be diagnosed if abnormal cells or too many or too few of a type of blood cell is found in the blood.

CBC tests can

Circulating tumor cell (CTC) test

This test helps detect, identify and count circulating tumor cells that have detached from the original tumor site and entered the bloodstream. This diagnostic test may be used to monitor metastatic breast, colorectal, and prostate cancers.

Flow cytometry

Flow cytometry is used to diagnose certain types of cancers, such as leukemia and lymphoma, and evaluate the risk of recurrence. The blood sample is treated with special antibodies and passed in front of a laser beam. If these antibodies get attached to cells, the cells give off light. The type of cancer cell is identified based on either the presence or the absence of certain protein markers (antigens) on a cell’s surface.

Cytogenetic analysis

A sample of blood cells is examined under a microscope to look for chromosomal changes. Cytogenetic analysis detects alteration in chromosomes and may identify actual genes that have been affected. The findings help diagnose specific types of blood cancers.

Gene expression profiling

This test helps identify cancer subtypes and risk factors. Gene expression profiling is mostly used as research tools and designing treatment protocols. This test uses a technique called microarray analysis to identify combinations of genes that are turned on or off in response to specific conditions. The test results help classify tumors and predict response to treatment and risk of disease relapse.

Immunophenotyping

Immunophenotyping identifies a specific type of cell in a sample of blood. Immunophenotyping can distinguish myeloid leukemia cells from lymphocytic leukemia cells, normal lymphocytes from leukemic lymphocytes, and B-cell lymphocytes from T-cell lymphocytes. This procedure helps determine the best cancer treatment.

Karyotype test

A karyotype test uses the 46 chromosomes of a cell to identify and evaluate changes in arrangement, size, shape, and number in a sample of blood. A dye called Giemsa may be used to easily view the banding pattern of chromosome pairs. This is also referred to as G-banding.

Blood chemistry test

Blood chemistry involves a group of tests that provide information about underlying cancer. Depending on the type of panel, these tests can measure

The results of the blood chemistry tests can indicate certain types of cancers, such as

Genomic testing

Genetic testing helps to understand if a person has a higher risk of developing cancer during their lifetime by checking for gene mutations. While most genomic tests are performed on tissue biopsy, a few blood tests are used for this purpose.

Common genomic tests and their indicative cancers are

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References
American Cancer Society. Tests to Find and Diagnose Cancer. https://www.cancer.org/healthy/find-cancer-early/tests-to-find-and-diagnose-cancer.html

National Cancer Institute. Screening Tests. National Institutes of Health. https://www.cancer.gov/about-cancer/screening/screening-tests

Cancer Research UK. Tests and Scans. https://www.cancerresearchuk.org/about-cancer/cancer-in-general/tests

University of Iowa Hospitals & Clinics. Cancer Diagnostic Tests and Blood Tests Word List. https://uihc.org/health-topics/cancer-diagnostic-tests-and-blood-tests-word-list

Hassan O. What Are the ASCO Guidelines for the Use of Tumor Markers in the Prevention, Screening, Treatment, and Surveillance of Breast Cancer? Medscape. https://www.medscape.com/answers/1668113-181364/what-are-the-asco-guidelines-for-the-use-of-tumor-markers-in-the-prevention-screening-treatment-and-surveillance-of-breast-cancer

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