DNA strand in bloodstream representing liquid biopsy

Decoding Cancer: How Liquid Biopsies are Revolutionizing Personalized Treatment

Lena Kashyap in Health & Wellness October 2026 • 4 min read.

"A new study reveals how analyzing circulating tumor DNA can unlock tailored therapies, offering hope for diverse cancer patients."

The fight against cancer is constantly evolving, with researchers seeking more precise and less invasive methods to understand and treat this complex disease. One promising avenue is the analysis of circulating tumor DNA (ctDNA), fragments of DNA shed by cancer cells into the bloodstream. This approach, often called a "liquid biopsy," offers a way to peek into the genetic makeup of a tumor without the need for traditional, invasive tissue biopsies.

Traditional biopsies, while essential, have limitations. They can be painful, carry risks, and may not always capture the full picture of a tumor's genetic diversity. Tumors evolve over time and can vary in different locations within the body. Liquid biopsies offer a potential solution by providing a more comprehensive and dynamic view of the cancer's genetic landscape.

A recent study published in Cancer Research sheds light on the power of liquid biopsies to identify actionable genomic alterations in a diverse group of cancer patients. This research demonstrates how analyzing ctDNA can guide personalized treatment strategies, offering new hope for improved outcomes.

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History

From Discovery to Clinical Practice

Chen et al.'s review traces liquid biopsy through its discovery histories, biomarker features, and clinical applications, describing its increasing use as a supplement to traditional biopsy in oncology. The term has become closely associated with blood-derived circulating biomarkers; other cell types discussed include circulating endothelial cells and cancer-associated fibroblasts. A 2025 history review says that, as technology and applications mature, liquid biopsy is expected to play a greater role in early diagnosis, treatment evaluation, and personalized treatment for cancer and other diseases.

Unlocking the Potential: Key Findings from the ctDNA Study

DNA strand in bloodstream representing liquid biopsy

The study, led by researchers at the University of California San Diego (UCSD) and Guardant Health, analyzed ctDNA from 670 patients with various types of cancer. The goal was to identify genomic alterations that could be targeted with specific therapies. The results revealed several important insights:

Prevalence of Actionable Alterations: Approximately 63% of patients had at least one alteration detected in their ctDNA. Notably, 48% of all patients had alterations that could potentially be targeted with existing drugs, either on-label (approved for their specific cancer type) or off-label (approved for other cancers).

Frequent Mutations: The most frequently observed alterations were in the genes TP53 (32.5%), EGFR (13.0%), KRAS (12.5%), and PIK3CA (9.1%). These genes play critical roles in cell growth, survival, and response to therapy.
Cancer-Specific Profiles: The study also found variations in the types of alterations depending on the cancer type. For example, head and neck cancers showed a higher number of alterations compared to brain tumors.
Brain Tumor Insights: While brain tumors were less likely to show ctDNA alterations (32%), the detection of even a single alteration could be valuable for treatment planning.

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Latest Research

Recent Reviews and Research Priorities

A May 29, 2026 review by Valpione et al. discusses how liquid biopsy applications in precision oncology might expand to provide a more holistic and personalized view of cancer. A May 23, 2026 review focuses on early cancer detection, therapeutic monitoring, and minimal residual disease (MRD), while also discussing challenges and regulatory perspectives. A 2025 review highlights potential in diagnosis, prognosis, and treatment monitoring, and says further research, clinical trials, and regulatory harmonization will be vital to realizing that potential.

Counterpoints

Limits in Testing and Treatment Decisions

In the phase 2a platform trial plasmaMATCH, ctDNA testing accuracy was reported as similar to tissue sequencing, but discordance remained for patients with low allele frequency mutations, pointing to room for assay development. Separately, the randomized phase 2/3 DYNAMIC-III trial describes the individual benefit of adjuvant chemotherapy in stage III colon cancer as uncertain. Together, these findings highlight that technical agreement and treatment decisions at the individual level remain distinct challenges.

Comparison

Comparisons Depend on the Measure

In the phase 2 CHRONOS trial, the chemotherapy-free regimen had a 30% response rate, compared with 8% and 21% in two other clinically based studies of rechallenge with chemotherapy or immunotherapy in the same setting. A systematic review and meta-analysis of ctDNA testing in advanced non-small cell lung cancer reported overall sensitivity of 0.69 (95% CI 0.63–0.74) and specificity of 0.99 (95% CI 0.97–1.00) for detecting any mutation. These figures describe different endpoints—treatment response in one setting and diagnostic accuracy in another—so they should not be treated as a direct head-to-head comparison.

The study underscores the feasibility and impact of using ctDNA analysis to guide cancer treatment decisions. By identifying actionable alterations, clinicians can select therapies that are more likely to be effective, potentially improving patient outcomes and quality of life.

The Future of Cancer Treatment: Personalized Approaches and Liquid Biopsies

The research underscores the potential of liquid biopsies to revolutionize cancer care. By offering a non-invasive and comprehensive view of a tumor's genetic makeup, ctDNA analysis can guide personalized treatment strategies, improve patient outcomes, and accelerate the development of new therapies. As technology advances and our understanding of cancer evolves, liquid biopsies are poised to play an increasingly vital role in the fight against this complex disease. The ability to serially monitor ctDNA also provides a powerful tool for tracking treatment response and detecting resistance early, allowing for timely adjustments to therapy.

Blood and tissue testing do not always agree

19.62 and 11.11 % of casesTissue testing alone was positive in 19.62% of cases, while plasma ctDNA alone was positive in 11.11%.^[1]

What blood-test results can and cannot establish

Agreement between blood and tissue results is not complete, and each method can identify positives the other does not. A blood result therefore does not simply reproduce the tissue result in every case.^[1]

How other testing evidence frames the comparison

Guidance describes tissue testing as preferred for many patients, while noting ctDNA can be used when quicker results matter clinically or tissue biopsy is not possible or appropriate. It also notes assay limits for detecting fusion events and copy number changes, and the possibility of false negatives.^[2]

Questions that remain about interpreting blood signals

When a variant is detected in plasma, how often does it come from tumor DNA rather than clonal hematopoiesis, in which blood-forming cells accumulate mutations and expand?^[3]
How clinically meaningful are assay-specific findings in prostate cancer, given the small cohort and the possibility that some guideline-based variants may be associated with clonal hematopoiesis?^[4]
How much does capturing DNA from multiple tumor regions improve the picture of tumor diversity compared with a tissue sample?^[3]

Terms behind ctDNA testing

Clonal hematopoiesis: The accumulation of somatic mutations in blood-forming stem cells, followed by expansion of cells carrying those mutations.^[3]
Concordance: The extent to which tissue and blood testing detect the same result.^[1]

Sources

Plasma ctDNA increases tissue NGS-based detection of therapeutically targetable mutations in lung cancers (pmc.ncbi.nlm.nih.gov)
ESMO recommendations on the use of circulating tumour DNA assays for patients with cancer: a report from the ESMO Precision Medicine Working Group - UCL Discovery (discovery.ucl.ac.uk)
Clonal Hematopoiesis in Liquid Biopsy: From Biological Noise to Valuable Clinical Implications (pmc.ncbi.nlm.nih.gov)
Concurrent Tissue and Circulating Tumor DNA Molecular Profiling to Detect Guideline-Based Targeted Mutations in a Multicancer Cohort (pmc.ncbi.nlm.nih.gov)

About this Article -

Written with AI assistance from published research, and reviewed by the Mystum team. See our About page for more information.

Everything You Need To Know

What exactly is a liquid biopsy and how does it work?

A liquid biopsy is a method of analyzing circulating tumor DNA (ctDNA), which consists of DNA fragments that cancer cells release into the bloodstream. It's a non-invasive way to understand the genetic makeup of a tumor, offering a comprehensive and dynamic view of the cancer's genetic landscape. Unlike traditional biopsies, which can be painful and may not fully represent the tumor's diversity, liquid biopsies provide a broader picture of the cancer's genetic profile.

Why is analyzing circulating tumor DNA so important in cancer treatment?

Analyzing circulating tumor DNA (ctDNA) through liquid biopsies is significant because it can identify actionable genomic alterations that can be targeted with specific therapies. The recent study showed that a large percentage of patients had alterations that could potentially be targeted with existing drugs, either on-label or off-label. This means that by understanding the specific genetic mutations driving a patient's cancer, clinicians can select therapies that are more likely to be effective, improving patient outcomes and quality of life.

Can you explain genomic profiling through liquid biopsies and what insights it provides?

Genomic profiling through liquid biopsies involves analyzing circulating tumor DNA (ctDNA) to identify genetic alterations in cancer cells. These alterations can include mutations in genes like TP53, EGFR, KRAS, and PIK3CA, which play critical roles in cell growth and survival. By identifying these specific alterations, clinicians can gain actionable insights into the cancer's behavior and select personalized therapies that target these specific mutations. This approach is transforming cancer treatment by providing a more precise and tailored approach to therapy.

Why are genes like TP53, EGFR, KRAS, and PIK3CA so important in the context of cancer?

The genes TP53, EGFR, KRAS, and PIK3CA are significant in cancer because they play critical roles in cell growth, survival, and response to therapy. Mutations in these genes are frequently observed in various types of cancer. For example, TP53 is a tumor suppressor gene, while EGFR, KRAS, and PIK3CA are involved in signaling pathways that regulate cell proliferation and survival. Understanding the specific mutations in these genes can help clinicians select therapies that target these pathways, potentially improving treatment outcomes.

How can ctDNA analysis actually help personalize cancer treatment?

ctDNA analysis can guide personalized treatment strategies by identifying actionable genomic alterations in a patient's cancer cells. This allows clinicians to select therapies that are more likely to be effective based on the specific genetic mutations driving the cancer's growth. Additionally, ctDNA analysis can be used to monitor treatment response and detect resistance early, allowing for timely adjustments to therapy. This personalized approach has the potential to improve patient outcomes and quality of life by tailoring treatment to the individual characteristics of their cancer.