Why precision biomarkers will change the future of breast cancer care

The most consequential changes in cancer biology can often occur before they become visible on a scan. Yet, modern cancer detection still relies heavily on identifying established disease: imaging can locate a tumour, while a biopsy can characterise its biology. These tools are essential, but they may not capture the biological changes that precede visible recurrence. Precision biomarkers offer a way to detect those changes earlier, when there is a greater opportunity to intervene.

Rather than waiting for disease to become visible, blood-based biomarkers can provide an earlier, dynamic view of what is happening inside a patient, creating an opportunity to detect changes sooner and intervene before they become clinically apparent.

This is particularly important in metastatic breast cancer, where the cells that drive recurrence and spread can enter the bloodstream long before a new tumour is detectable on a scan. In triple-negative breast cancer (TNBC), one of the most aggressive forms of the disease, metastasis is responsible for more than 90% of deaths. If we can detect these cells before they establish new tumours in vital organs, we may have a critical window to intervene earlier, potentially changing the course of disease for patients.

Here’s a closer look at how blood-based biomarkers could help detect recurrence earlier, guide treatment, and inform the development of new therapies.

1. Liquid biopsy can reveal what imaging cannot.

Historically, oncology has looked primarily to tissue biomarkers to understand tumours. However, blood offers a more dynamic view and can reveal cancer cells circulating before metastatic disease is visible on a scan.

This is particularly relevant because the cells that drive metastasis may represent a small fraction of the primary tumour. Standard chemotherapy, immunotherapy, and radiotherapy can eliminate much of the tumour bulk, while a population of aggressive cells may survive, remain dormant, and later enter the circulation. From there, these cells can seed distant organs and establish new tumours.

New biomarker technologies can identify these aggressive metastatic cells in blood, with detection sensitivity down to a single cell. That creates a window for earlier intervention: rather than waiting for metastatic disease to become visible, we can begin using changes in the blood to understand whether disease is emerging and how it may be progressing.

2. Earlier signals could change the way oncologists treat patients.

The value of a biomarker goes beyond detection; it can change clinical care. This is the logic behind molecular residual disease monitoring: using dynamic biomarker signals, rather than imaging alone, to guide when to escalate, de-escalate, or stop treatment.

Consider a patient who has completed treatment and receives a reassuring scan. A clear scan tells us there is no visible tumour, but it does not necessarily mean the cancer is gone. If aggressive metastatic cells have already entered the bloodstream, recurrence may be underway long before a new tumour becomes visible on imaging.

If the number of aggressive cells begins to increase, treatment could be restarted or adjusted before recurrence becomes visible. If those signals remain absent, regular blood monitoring could eventually help clinicians determine when treatment can safely be reduced or stopped.

This is important because cancer treatment carries a significant burden. Many therapies are toxic, and clinicians do not always have an objective biological endpoint to tell them when treatment has achieved its ends. Continuing treatment unnecessarily exposes patients to additional toxicity, while excessive drug exposure can also contribute to resistance. A more dynamic measure of disease could help clinicians treat when treatment is needed, intervene when the disease begins to change, and avoid treatment when there is no evidence that it is necessary.

The benefit extends beyond the patient. More precise treatment decisions could reduce unnecessary use of drugs, clinical resources, and healthcare infrastructure, while giving clinicians a better opportunity to intervene before recurrence becomes harder to treat.

3. Biomarkers can reshape drug development, not just patient monitoring.

When we can identify the cells associated with metastasis in the blood, we can also isolate and study them. That gives researchers an opportunity to understand the biology of the cells that survive treatment and ultimately cause recurrence, and to develop therapies designed to specifically target them.

This creates an important feedback loop between biomarker research and therapeutic development. The biomarker tells us which cells matter. Studying those cells tells us what makes them vulnerable. That biology can then inform the development of new treatments.

In this model, biomarkers are not simply diagnostic tools used to determine whether a treatment has worked. They become part of the engine driving drug development itself. By identifying the aggressive “seed” cells that drive metastasis, researchers can develop treatments designed to target them specifically – bringing precision oncology closer to truly precision treatment.

The future of precision oncology is a dynamic picture of the patient

Looking ahead, liquid-biopsy precision testing could fundamentally change routine cancer care by giving hospitals a dynamic compendium of the patient that brings together cancer burden, immune activity, and other biological signals in one continually updated view. Instead of specialists working from separate snapshots, it could create a unified picture of the patient across disciplines, enabling more coordinated and informed decisions.

But technology alone will not get us there. We need greater investment in large-scale clinical trials to establish whether these signals translate into better outcomes, and we need to equip clinicians and hospitals to use them in practice. That means funding the science beyond the proof of concept, incorporating blood-based biomarkers into clinical education, and building the evidence needed to change standards of care – all through a simple, minimally invasive blood test.

If we can make this approach part of clinical practice, we could change outcomes for many breast cancer patients, particularly those with Stage 3 or 4 disease or those at high risk of recurrence, and save thousands of lives.

About the author

Professor Sudha Rao, PhD, is a globally recognised translational scientist and biotechnology executive with over 20 years of experience spanning pharmaceutical R&D and early clinical development. As chief scientific officer of Kazia Therapeutics, she leads the company’s integrated oncology strategy and next-generation pipeline, including PI3K/mTOR inhibition, PD-L1 protein degradation, and SETDB1-targeted epigenetic programmes. The scientific originator of the epigenetic framework underlying paxalisib, she has played a pivotal role in establishing PI3K/mTOR signaling as a driver of epigenetic reprogramming.