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Can we use a simple blood test to detect cancer?

Breast cancer could be detected by a blood test, according to reports that appeared on 29 September 2016. Scientists at Australia National University (ANU) are working with their counterparts in France to this form of cancer detection, which is much less invasive and expensive than other tests like biopsies, a reality.

Researchers say they will be able to detect breast cancer in the blood by checking the ratio of certain isotopes, carbon 13 and nitrogen-15 – which are variants of particular chemical elements – in a sample of tissue.

However, the test is still about ten years away from being used in the clinic, although research in this area is booming. Scientists have been looking for, and finding, ways to track various types of blood cancer for some time. In fact, blood-based tests for solid tumors in not a new development.

Currently, some tests are used to detect proteins found in higher levels in certain cancers. These are called “tumor markers” CA15-3 and include breast cancer, pancreatic CA 19-9 and CA-125 cancer ovarian cancer.

However, they are relatively non-specific. For example, a person with ovarian cancer have high levels of CA-125, but high levels do not always mean that the person has ovarian cancer. They may indicate a benign tumor in the ovary in place. Neither these tests can assess how cancer changes over time. So how are the new blood test being developed to hit the target?

First, a little about cancer

Cancer is a disease of the genome, which means that characterizes and caused by changes in our genes that can lead to a healthy mutated in a cancer cell.

Cancer remains difficult to treat because every cancer is different, even within the same type of cancer, such as breast or colon. Every tumor has a genetic code that makes it unique, but there are also genetic differences within the tumors themselves. And tumors can evolve over time become resistant to treatment.

best strategies to guide treatment, all cancer cases must be independently evaluated and monitored for changes over time. With recent advances in cancer genetics, we can better understand the difference between cancer and normal cells and locate where things have gone wrong.

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When cancer cells break down and die, they release their contents, including their DNA with their unique genetic code, into the bloodstream. This free-floating DNA is known as circulating tumor DNA (ctDNA).

Through the development of sophisticated techniques for measuring and sequence of this ctDNA into the bloodstream, scientists can get a snapshot of the cancer itself, which is known as a “liquid biopsy”. Taken over time, this type of blood samples would show doctors whether treatments are working and whether tumors are developing resistance.

This is like the assessment of changes in the family diet by screening dumpsters. This can be done several times without disturbing the privacy of the family.

liquid biopsies

Classical methods for dynamic monitoring of cancer, such as tumor markers and analysis to estimate tumor size, can not be evaluated genomic tumor status.

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The biopsies are becoming standard care in the departments of pathology.

Genetic analysis of a sample of the tumor, also known as biopsies, are becoming standard care in the departments of pathology. However, biopsy provides only a snapshot of genomic changes in tumor that particular piece. A biopsy also commonly requires an invasive surgical procedure, so it can not be done frequently.

So if changes are occurring over time, decisions based on the results of age will be obsolete. Best methods for studying tumor progression can greatly improve cancer care.

One of the most advanced examples of liquid biopsy application in the treatment of cancer is in the treatment of lung cancer. The researchers found that about 60% of lung cancers treated with a drug to target something called the epidermal growth factor receptor (EGFR) in cancer cells become resistant to therapy. Then they found the culprit responsible for resistance :. A small change in the EGFR gene, known as T790M mutation

Scientists were able to devise a new drug to target T790M. So when patients develop resistance to first-line therapy, which could be treated with this new drug.

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In parallel, the development of a test to detect this mutation in blood plasma or urine ctDNA allows patients to be monitored and timely treatment change that occurs when resistance begins to show.

Our recent study showed that treatment response may be followed by measuring ctDNA in the blood of patients with melanoma. A decrease in the amount of ctDNA accurately reflects shrinkage of cancer. But most importantly, increased ctDNA indicated that the cancer would return.

This is important because it can accelerate change treatment when the cancer is still under control and the patient’s health is not compromised. We could also detect the development of melanoma mutations in their genes learned to become resistant to treatment. This can inform treatment strategies as more drugs available for metastatic melanoma.


ctDNA addition, there is an intensive investigation of the other components of the blood that can reveal what is happening in the cancer patient. These components include cancer cells are released into the circulation, or circulating tumor cells called CTC, small droplets called exosomes released by cancer and other types of genetic material and proteins.

A team of researchers from the Walter and Eliza Hall Institute recently showed that patients with colon cancer with ctDNA detectable in the blood after the tumor was removed by surgery, are at high risk of the cancer coming back. The use of such a test will identify these high-risk cases so the residual cancer can be removed.

promises of what we can discover about the patient’s tumor from a simple blood sample are still scratching the surface. As this window expands, better and more complex picture emerges cancer, empowering researchers and clinicians with more information to deploy the arsenal against cancer available.

Author: Elin Gray, post-doctoral researcher in melanoma, Edith Cowan University

Courtesy: The Conversation

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