The way liquid biopsies are revolutionizing the process of cancer screening and treatment planning

By : Saanvi Talwar

There is no doubt that the war on cancer has suffered because of the inability to use conventional diagnosis tools. The tissue biopsy where doctors extract part of a tumor and have it tested has been the eventual gold standard in terms of gaining knowledge of the type of cancer, its stage and genetic makeup. However, such procedures are invasive, painful, costly and sometimes even dangerous given the location of the tumor. But cancer does not standstill, it develops, metastasizes, and evolves. This incompatibility has made doctors powerless in getting hold of the whole picture of disease of a patient. Then there is liquid biopsies, an emerging technology that relies on a routine blood sample to carry out an examination of cancer-derived material flowing in the blood. Liquid biopsies are emerging as a novel, less invasive and more comprehensive method of screening to detect cancer, determine treatment and assess disease progression. Neither are a mere technical innovation, but are indicative of a paradigm shift in thinking when it comes to the detection and management of one of the deadliest diseases affecting the world. 

Among the strongest influences of the liquid biopsies is the early cancer detection. The sooner cancer is diagnosed the more likely it can be successfully treated, yet in a number of cancers there are no effective screening procedures. Although breast cancer and colon cancer may be detected by using mammograms and colonoscopies, respectively, there are no regular tests to detect pancreatic, ovarian, or liver cancer that are highly deadly. The solution can be found in liquid biopsy technology that can identify the genetic tumor signals which cannot be captured using scans. Multi-cancer early detection (MCED) assays, which are still in development such as those at Grail, Guardant Health, and Freenome, could detect dozens of types of cancer based on a single blood sample. Research has revealed that ctDNA presents the potential to detect cancers long before the manifestation of clinical symptoms due to months or even years. In the case that such tests were adapted on a broad level, they would even revolutionize the physicals that individuals receive on an annual basis, to the extent that cancer screening could be done as conveniently as a cholesterol test. Not only would this save lives, but it would also cut costs of treatment of advanced cancers which tend to be more serious and costly to the patient.

Another area in which precision is critical is in the design of treatment plans, and liquid biopsies are changing that as well. Conventional biopsies can be incomplete, failing to represent the genetic variability that occurs throughout a given tumor or between a metastasized tumor across organs. This becomes an issue as cancer cells will rapidly evolve and gain resistance to the treatments and will overtime develop resistance to them. Liquid biopsies resolve this problem as they can capture the tumour DNA that has been shed to many locations around the body to provide a more comprehensive picture of the genetic profile of the cancer. This knowledge confers value in that the oncologists will be able to utilize this ample information to adopt precise types of treatment that correspond with the mutations that are fueling the cancer in a patient. An example would be of a lung cancer patient with ctDNA containing mutations in their EGFR gene: doctors can prescribe them EGFR inhibitors that target that specific mutation. Subsequently, in case of the emergence of new mutations in ctDNA indicative of resistance to the drug, the treatment plan can be adjusted. This capacity enables treatment to become more responsive, dynamic and personal to cancer in a way that was never available in the past. 

The second significant strength of liquid biopsies is that they help to monitor dynamic disease progress and treatment response. It can even take weeks or months to determine the success of a tumor shrinking, stabilizing, or expanding by using imaging scans. Instead, ctDNA levels rise and fall in blood over a period of days or weeks, providing a physician with feedback about a treatment well before the process of a clinical trial can be performed. As an example of the possible use of this information, assuming the presence of elevated levels of ctDNA at the start of oncological treatment and its persistence during chemotherapy, the oncologist can switch to alternative treatment within a short time without having to wait months to assess the treatment with the help of imaging studies. Such proactive monitoring eliminates the risks of patients being exposed to a poorly working treatment and the side effects of using such a treatment. Liquid biopsies have also been shown to be able to detect residual minimal disease (MRD)- small quantities of cancer remaining in the body following surgery or chemotherapy which might not be evident on scans. Early MRD detection enables doctors to address the problem earlier before it results in a relapse and, therefore, increases the long-term survival rates.

Another important consideration that makes the liquid biopsies exciting is the view on its accessibility. In patients whose tumors are located in difficult-to-biopsy locations, including the brain, lungs and pancreas, tissue biopsies are impractical, hazardous or even impossible to repeat. Compare this with blood draw, which is safe, makes it relatively inexpensive and it can be routinely taken so the doctor can track changes of the patient over time. This has made cancer treatment to be friendlier to patients and does not interfere so much with their daily lives. Besides, liquid biopsies are likely to bring cancer care to the masses since they are able to bring sophisticated diagnostic equipment to regions lacking adequate healthcare facilities. Although tissue biopsy requires specialized equipment and surgical facilities, as well as pathologists, a liquid biopsy only requires access to the laboratory and the use of sequencing technology as it only needs the collection of blood samples. With the decline in costs, this could help provide state of the art cancer screening and monitoring to a wide range of communities and countries where the traditional cancer biopsy is not possible, closing the gap on cancer care around the world. 

Although it promises, the use of liquid biopsy is not perfect and there are obstacles that need to be dealt with, prior to liquid biopsies being able to replace conventional technologies. Very early cancers do not all release ctDNA that can be identified in the blood, which is why even cancer-positive results are not always correct. Another challenge of science is to differentiate cancer causing mutations and non-causing mutations that occur naturally with age. Moreover, although liquid biopsies are capable of determining the presence of a mutation, they do not necessarily indicate where it retrospectively started in the body, namely what tissue (organ). This is important information, especially when it comes to selecting the proper treatment. Nevertheless, studies are progressing at a fast rate. There is increasing evidence that the performance and usefulness of these tests is accurate and medical evidence showing in clinical trials and regulatory bodies are easily approving the use of liquid biopsy-based diagnostics with some applications e.g. detecting mutations in lung cancer patients. With rising accuracy, falling costs and evolving clinical guidelines, liquid biopsies will make the shift to become a core functionality in oncology practice, rather than a complementary tool.

Concisely, liquid biopsies are transforming how we detect, plan and manage cancer treatment. Their ability to facilitate detection earlier on, more accurate treatment decisions and even track disease progress in real-time provides unprecedented personalization in the treatment of cancer. They are non-invasive and therefore can be available at relatively low costs and burdens to patients, and they are scaling, which would allow screening the entire population with cancer, identifying millions of patients. Despite the difficulties, the trend is still unmistakable: liquid biopsies will be the new pillar of contemporary oncology that will enable the transition of cancer management to non-reactive to proactive, and invasive to minimally invasive. Moving forward, this technology can promise to not only prolong the lives of cancer patients, but also raise the quality life enjoyed by millions of such patients in this captivating world.

Citations 

The Emerging Role of Liquid Biopsies in Revolutionizing Cancer Diagnosis and Therapy, 17 August 2023, https://pmc.ncbi.nlm.nih.gov/articles/PMC10505053/. Accessed 20 August 2025. Bartosch, Jamie. “Liquid biopsy: A new tool for identifying and monitoring cancer.” UChicago Medicine, 24 January 2024, 

https://www.uchicagomedicine.org/forefront/cancer-articles/liquid-biopsies. Accessed 20 August 2025. 

“Biomarker Tests and Cancer Treatment.” American Cancer Society, 21 September 2022, https://www.cancer.org/cancer/diagnosis-staging/tests/biomarker-tests.html. Accessed 20 August 2025.