Codes Hidden in the Blood: Personalized Treatment with Liquid Biopsy in Lung and Breast Cancer

1. The Era of "Liquid Biopsy" in Cancer Diagnosis and Monitoring

In cancer treatment, choosing the right smart drug means racing against time and understanding the tumor's genetic makeup completely. A recent expert opinion paper published by the European Society of Pathology reveals the critical and transformative role of "Liquid Biopsy" taken from blood in oncology.

Analyzing the free DNA fragments (ctDNA) shed into the bloodstream by tumor cells offers an alternative that does not tire the patient and can be repeated continuously, in situations where a tissue biopsy cannot be performed, is risky, or is insufficient for genetic testing.

2. Life-Saving Speed and Resistance Monitoring in Lung Cancer

The paper explains in detail how liquid biopsy has changed treatment management in advanced-stage non-small cell lung cancer (NSCLC):

Rapid Treatment Decisions: In lung cancer, reaching the tumor tissue or taking a biopsy is not always possible or safe, and the number of cells in the tissue sample obtained may be insufficient. In such cases, liquid biopsy detects targetable mutations in the tumor (EGFR, ALK, etc.) far more quickly, allowing personalized treatment (smart drugs) to begin without losing time.
Detecting Resistance Mechanisms: Resistance to the smart drugs used in lung cancer can develop over time. When the disease progresses, instead of putting the patient through another difficult tissue biopsy, the new resistance mutations developed by the tumor can be identified quickly with a liquid biopsy from blood, and the treatment plan can be updated.

3. Real-Time Tumor Monitoring in Metastatic Breast Cancer

In metastatic breast cancer (especially the hormone-sensitive HR+/HER2- subtype), liquid biopsy is now moving to the center of the standard clinical approach:

Catching Hidden Resistance Mutations: In breast cancer, acquired resistance mutations against hormone therapies (for example ESR1 mutations) can develop over time. These mutations are usually absent at the moment of initial diagnosis and emerge only under treatment pressure.
Seeing Tumor Heterogeneity (Diversity): Resistance mutations such as ESR1 may be present only in tumors located in certain parts of the body (this is called a subclonal or polyclonal structure). A tissue biopsy taken from a single site may miss these mutations, whereas liquid biopsy collects all the DNA shed into the blood and therefore reflects the overall genetic map of the disease throughout the body.
Early and Dynamic Intervention: Alongside resistance mutations such as ESR1, liquid biopsy can simultaneously detect core targets that come from the root of the disease, such as PIK3CA and AKT1. This makes it possible to steer treatment toward next-generation smart agents (for example oral SERDs or PI3K inhibitors) months before the tumor shows any sign of growth on imaging.

4. Our Strategy: Combining the Power of Tissue and Blood

The report of the European Society of Pathology issues a vital warning: liquid biopsy does not completely replace tissue biopsy, it complements it. For example, tissue analysis is still the gold standard for determining the histological subtype of the tumor, testing eligibility for immunotherapy (PD-L1), or finding targets that cannot be detected in blood because there is not enough tumor DNA (false negativity).

At our clinic, we apply exactly this "integrated" strategy to decode the complex structure of cancer:

We blend both tissue and liquid biopsy data through Comprehensive Genomic Profiling tests that meet international standards.
To prevent the false alarms and confusion that age-related genetic changes accumulating in the blood (CHIP) can create in blood tests, we analyze test results in depth with our experienced Molecular Tumor Board (MTB).
We do not settle for a single snapshot of the tumor. With liquid biopsy we follow the evolution of the disease over time closely, and in the light of the most current evidence in the literature we design the most accurate and safest "Personalized Combination" treatments for our patients.

Conclusion

The genetic code of cancer does not stay fixed during treatment, it changes. When the detail offered by tissue biopsy is used together with the speed and repeatability offered by liquid biopsy, it becomes possible to see that change in time and to update the treatment at the right moment.

To learn more about molecular monitoring with liquid biopsy and personalized combination strategies, you can contact our clinic.

Sources and Further Reading

Expert Opinion Paper on Liquid Biopsy and Molecular Pathology: Fusco, N., et al. (2026). Liquid biopsy in solid tumours: expert opinion paper of the European Society of Pathology. Virchows Archiv.