New Blood Tests Detect Cancer – Is It True?

Lately, there’s been a buzz going around about the cancer research sector over the blood emergence tests that detect cancer has reached a crescendo. The new blood test can now detect more than 50 types of cancer, along with its place of origin in the body. It can detect even before the symptoms develop.

Historically, blood tests called liquid biopsies have not been a useful way to detect cancer. Research and efforts made it easy to detect multiple types of cancer moving swiftly towards widespread consumer use.

While scientists agree that more human clinical trials need to push this technology forward, the science so far has proven to be sound. These tests are vast and could help to save countless lives due to early detection.

Machine learning and biology meet

The test works by a type of DNA released by tumor cells. It sheds into the blood, where it is known as cell-free DNA (cfDNA). It can be challenging to identify the tumor-specific cfDNA because many other cells also release DNA into the blood.

The test can detect DNA from cancer cells by using the in DNA. It detects it by the addition in the chemical named methyl group that is associated with tumor growth.

After isolating cfDNA from the blood sample and sequencing it to find the methylated parts, healthcare professionals feed the results into the computer that recognizes DNA from noncancer and cancer cells.

93% accuracy

The study with about 15,000 people among which 4,000 roughly had cancer. The researchers made the inclusion of about 50 types of cancer in the study. The test was accurate in 93% of samples and could accurately predict where in the body the cancer is first developed in 96% of the samples.

About 0.7% of the false-positive rate means that less than 1% of people would have an inaccurate diagnosis of cancer in the test.

Compared to the screening programs like breast cancer with a false positive rate of around 10%, the benefits of this new approach are clear.

New hope for ‘hard to detect’ cancers

Researchers are still validating the test in large, population-level studies. Although the results of these trials are yet to come, scientists are hopeful.

Scientists are hopeful that the test results will help diagnose cancers where the symptoms do not develop for a long time. The doctors are not usually able to diagnose until a later stage.

The study looked at the 12 most dangerous types of cancer, including ovarian, lung, and pancreatic cancers, which account for over 60% of all cancer-related deaths every year in the U.S.

Currently, there isn’t any way to screen most of these cancers until the development of symptoms. However, this blood test accurately detects more than 67% of them.

Two new tests are approved

The Food and Drug Administration (FDA) recently gave approval for two blood tests that can be helpful in guiding the treatment decisions for people with cancer.

The tests, FoundationOne Liquid CDx and Guardant360 CDx are made by different companies and were approved separately.

Oncologists have historically based treatment decisions on features like the organ in which cancer starts to grow, whether cancer has spread, and whether the patient has other health conditions.

According to the National Cancer Institute, now they often use genetic changes in the tumor.

Certain targeted immunotherapies and therapies work best against tumors with specific genetic changes. The newly approved blood tests identify genetic changes, including mutations by scanning DNA in the blood.

Are the tests sensitive enough?

When the liquid biopsies came into being, the major question was, “if and when you see a genetic change in the blood, can you trust that it also exists in the tumor?” But the consequence is that genetic changes found in the blood accurately represent those present in the tumor. However, there can still be differences between the results of tissue-and-blood-based tumor profiling tests. The differences may not be because of the blood test’s accuracy, but because of tumor biology.


Many times it becomes tough to find enough tumor in DNA in the patient’s blood for a test to pick up any type of genetic change. In some way, it could be just luck, whether or not you happen to grab the sample of blood with enough DNA. For these cases, FDA recommends the patient to get a tissue biopsy to check for genetic changes. However, reducing deaths from this new technique is a once-in-a-lifetime opportunity to bring potentially life-altering innovative technology to patients.

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