Is There A Blood Test For Cancer?

Is There A Blood Test For Cancer

Despite the strides made in treating it, the word “cancer” is still a frightening one. Cancer is in fact the second biggest cause of death in the US with 602,350 (2020) deaths per year. However, despite the number of cases and the worry surrounding the disease, many developments have been made in the treatment of cancer.

The advancement of cancer treatment technology – detection chiefly among them, has greatly improved survival rates. As of 2019, 67% of US citizens diagnosed with cancer lived for more than five years and 45% for more than 10. The survival rate for five-plus years is also predicted to increase by approximately 31% by the end of the decade.

There are a vast array of diagnostic health testing services including blood tests. Blood tests are crucial for early cancer detection, as well as other diseases. 

How Are Blood Tests Used To Diagnose Cancer?

Firstly blood tests often diagnose cancer instantly under a microscope. For example, blood tests can diagnose cancer if cancer cells are visible under a microscope. However, there are also other ways a blood test can help detect cancer. For example, blood test results may show certain blood proteins, and other substances created by cancer are present.

However, blood tests along with giving clues about your overall health, are used in conjunction with other tests to diagnose cancer. A number of different blood tests are used to help detect cancer.

Traditional diagnostic testing should not be neglected, however. X-rays, MRI scans, and other forms of testing can be extremely beneficial in cancer detection. In conjunction with blood testing, these can provide an additional layer of early detection. Online services have even streamlined and simplified the booking process. This means you could potentially book a diagnostic test and be seen on the same day, for near-instant peace of mind or detection. 

What Blood Tests Are Used In Cancer Diagnosis?

Complete blood count

A Complete blood count or CBC is used to count both red blood cells and white blood cells. A low count of white blood cells may indicate blood cancers or bone marrow cancers. This includes leukemia, lymphoma, and multiple myeloma. Conversely, a high count of white blood cells can in some cases indicate cancer such as leukemia, or lymphoma.

Similarly, a low count of red blood cells can also indicate cancer like Leukemia, lymphoma, and multiple myeloma. This is because cancer will damage the bone marrow and crowd out red blood cells.

Blood cancers like Leukemia and lymphoma may also be present if there is a low platelet count.

Protein blood tests

A protein blood test is known as an electrophoresis blood test. This blood test separates the proteins in the blood by electric charge. This is done to find any abnormal substances in the blood which are known as M proteins. This can indicate a type of cancer named myeloma, or multiple myeloma.

Tumor marker tests

Tumor marker tests can be used to try and find chemicals made by cancer cells in the blood. Prostate cancer and ovarian cancer can create tumor markers in the blood. However, tumor markers are usually not enough for diagnosing cancer. This is because healthy cells can produce these types of chemicals, and other conditions can cause tumor markers.

Circulating tumor cell test

A circulating tumor cell test can be used to help find cancer cells in the blood. Cancer cells in the blood may have broken down from the body and spread to other areas. This is why it is normally used after cancer diagnosis, to determine the spread of the disease. This blood test is most commonly used when dealing with breast cancer, colon cancer, and prostate cancer.

Galleri test

This type of blood test looks at DNA in the blood. In particular, it is used to find cell-free DNA (cfDNA). This is shed by both tumor cells and healthy cells. The difference is that patterns of chemical changes are different in these cells. This can be discovered by using genetic sequencing technology and artificial intelligence.

This test is intended both to detect cancer signals and to find out exactly where the cancer signals are coming from in the body. However, its use is recommended in collaboration with other laboratory tests to diagnose cancer. Although, clinical trials have shown that these blood tests can detect 50 different types of cancer. This is with a low false-positive rate of 0.5%.

Cancer screening tests have shown that this type of testing is not good for finding cancer early. It is better used to detect later-stage cancer and to locate the cancer signal.

Most Common Types Of Cancer In The US

Blood tests are an excellent tool in helping to form a cancer diagnosis. They are especially helpful in certain cancers like blood and marrow cancers. However, traditional screening such as a physical examination may be the best, first course of action, for the most common cancers.

2021 figures by National Cancer Institute

Cancer Type Estimated New Cases Estimated Deaths
Breast (Female – Male) 281,550 – 2,650 43,600 – 53,000
Prostate 248,530 34,130
Lung (Including Bronchus) 235,760 131,880
Colon and Rectal (Combined) 149,500 52,980
Melanoma 106,110 7,180

Blood Tests For Cancer Diagnosis: Summary

Cancer remains a harsh reality that many of us will face. As the second-largest killer in the US, many have become accustomed to its devastating effects. However, thanks to better screening and more efficient cancer treatment, many more people are surviving the disease.

Blood laboratory tests have been instrumental in helping find cancer quickly so early treatment options can begin. A complete blood count (CBC) is a helpful tool in finding certain types of cancer, such as blood and bone marrow. This test uses blood samples to look at red and white blood cell numbers as well as blood platelets. High or low numbers in a blood sample can indicate the presence of cancer.

Protein cancer blood tests use an electric charge to find M proteins. M proteins can indicate the presence of myeloma. A tumor marker test is used to find chemicals that are sometimes made by cancer cells. However, other lab tests are needed to make a diagnosis.

Circulating tumor cell tests are used to discover if blood cells are circulating with cancer cells. Again this is normally only used with other lab tests to diagnose the disease or, to check the progress of cancer treatment.

The Galleri blood test is relatively new in comparison to other blood tests. This test will find cell-free DNA and differentiate cancer cells and normal cells. This is done by monitoring how they change chemically using sequencing technology and artificial intelligence. 

This test can help identify 50 different types of cancer. However, tests have shown it is less effective in finding early signs of cancer such as stage 1.

Blood tests can indeed help identify cancer, or be used to check the progress of treatment. However, blood tests usually require further testing before a diagnosis can be accurately made.