Detecting cancer in its early stages can help give doctors and patients options for treatments plans. Tissue biopsies involve physically extracting and analyzing parts of suspicious lumps or tissues to determine if they are cancerous. Since this technique involves tools like large needles, endoscopes, and/or open surgery, if patients are unable to undergo these invasive measures, determining a prognosis can be challenging. Researchers have been investigating a new form of biopsy that can detect cancerous cells and molecules through bodily fluids.

CTC, ctDNA, and Liquid Biopsy

In 1898, an Australian physician by the name of Thomas Ashwood discovered circulating tumor cells (CTC) in one of his patient’s blood. He postulated that this might be an explanation for why multiple tumors appeared in different parts of cancer patients’ bodies.

Since Ashwood’s discovery, scientists, clinicians, researchers, and engineers have been trying to find a way to detect tumors through bodily fluids. There are a variety of tests of liquid biopsies that can identify various forms of cancerous materials including DNA, RNA, proteins, exosomes, and whole cells. Thesetests use various bodily fluids including blood, urine, saliva, cerebrospinal fluid.

One of the most exciting areas of liquid biopsy research is in the biomarker field for circulating tumor DNA (ctDNA). Instead of just using traditional cancer screening methods like tissue biopsies, researchers are looking into using ctDNA to help create a more holistic picture of a patient’s diagnostic and prognostic results before, during, and after treatment.

Scientists are using ctDNA biomarker screening tools like BioChain’s cfPure™ Cell Free DNA Extraction Kit for fast and easy sample preparation and analysis. This kit isolates cell free DNA with BioChain’s original  silica-coated magnetic bead technology. Since this test takes only an hour, this means that more samples can be collected, giving researchers more data points and information to help diagnose their patients.

Although liquid biopsies could replace or supplement traditional screening methods in the future, there are still some questions that researchers and clinicians need answer before it becomes a widely standardized tool.

Liquid Biopsy’s Current Limitations

The success of a clinical method resides in its ability to be reproduced by anyone that can follow the procedures. Since there is a huge variation in the mutations and other indicators of not only various cancers, but variations in the development of a type of cancer, creating a cohesive catalogue of biomarkers to use for liquid biopsy is the challenge researcher face today. Even when researchers unlock the clinical key to biomarkers, liquid biopsy might detect tumors too early.

One of medicine’s highest tenets is to make sure everything that is done benefits the patient. Sometimes aggressive cancer treatments can do more harm to the body than another course of action. Since liquid biopsies detect tumors early on, there is a fear that it will detect slow growing or early stage tumors that might not continue to grow. Treating these two kinds of tumors might be deleterious to the patient’s health.

In order for liquid biopsies to enter the wide use clinical stage, scientists will need to standardize four things: detecting cancer at an early stage with reliable biomarkers, distinguishing between benign and cancerous tumors, and determining if the tumor is fast pace vs slow growing.

The Future Of Liquid Biopsy

Despite the need for more clinical research, scientists are already looking to future scenarios where liquid biopsy could be used to help patients.  Four applications for liquid biopsy are screening high risk patients, confirmation of diagnoses arrived at by other means, tracking the effectiveness of a particular cancer treatment, and assisting clinicians in choosing the best possible treatment for a specific patient.  Specifically, high risk individuals with a hereditary history of cancer could be proactively screened to catch early stage cancers while they can still be treated.   Liquid biopsy can potentially be used in conjunction with other tests like MRIs and tissue biopsies to get a increase the certainty of the a specific diagnosis, and help doctors begin treatment more quickly. A study conducted by the The National Cancer Institute found that their liquid biopsy tests correlated with positive responses to certain chemotherapy treatments. The hope here is that doctors can be given information that allows them to pick a treatment that works the first time – before a cancer grows out of control.  Lastly, liquid biopsy could provide real time results about the effectiveness of a treatment – giving doctors the chance to switch from an ineffective treatment to a more effective one more quickly.  All of these future applications share one important quality.  They save precious time, and timely treatment saves lives where cancer is concerned.

Michelle Kostuk is a freelance science journalist. She is passionate about translating scientific research into compelling stories. Currently located in Tucson, Arizona, she holds a Bachelor’s of Science in Ecology and Evolutionary Biology from the University of Arizona.