Oncologic biomarkers are biological measurements that indicate the presence, progression, or response to treatment of a cancer. Their usefulness includes diagnosis, patient stratification, prediction of therapeutic response, and disease monitoring. In modern oncology, oncologic biomarkers are the foundation of personalized medicine, enabling the selection of targeted therapies, optimizing clinical trials, and improving disease follow-up.
What are oncologic biomarkers?
An oncologic biomarker is any measurable characteristic—molecular, histologic, imaging-based, or physiologic—that provides information about biological processes related to cancer. These biomarkers can be detected in tumor tissue, blood, or other body fluids, as well as through imaging techniques. Key clinical applications include diagnosis, prognostic stratification, prediction of response to specific treatments, and monitoring response and recurrence.
Types of oncologic biomarkers
Diagnostic biomarkers: Detect the presence of cancer or help confirm the diagnosis. Example: PSA in prostate cancer (controversial due to specificity).
Prognostic biomarkers: Provide information about the likely course of the disease regardless of treatment. Example: gene-expression risk scores (Oncotype DX in breast cancer).
Predictive biomarkers: Predict the likelihood of response to a specific therapy; essential for personalized medicine. Example: EGFR mutation predicting response to tyrosine kinase inhibitors in lung cancer.
Pharmacodynamic / response biomarkers: Measure the direct biological effect of a treatment (reduction of a target protein, changes in signaling). Useful in early phases of drug development.
Susceptibility / risk biomarkers: Indicate predisposition to develop cancer (germline BRCA1/2 mutations).
Recurrence / monitoring biomarkers: Detect residual disease or recurrence after treatment; include circulating tumor markers and imaging-based measurements.
Molecular / histochemical diagnostic biomarkers: IHC, FISH, PCR to detect specific alterations in tissue.
Oncologic biomarkers allow selection of targeted therapies and immunotherapies, stratify patients in clinical trials, and speed up drug development through pharmacodynamic markers. Integrating oncologic biomarkers into clinical practice improves treatment personalization and optimizes outcomes.
Clinical and research relevance
Therapy selection: Predictive biomarkers are the basis of targeted therapies and personalized immunotherapies.
Clinical trial stratification: They enable study designs with populations more likely to benefit.
Treatment monitoring: ctDNA and serum markers help assess response and detect early relapse.
Drug development: Pharmacodynamic and mechanism biomarkers are essential in early phases.
Limitations and considerations
Despite their usefulness, oncologic biomarkers have limitations: variable sensitivity and specificity, differences between platforms (IHC, PCR, NGS) and cutoff points, tumor heterogeneity that limits how representative a single biopsy can be, and the need for clinical validation and regulation before widespread adoption. Interpretation requires clinical context, and often combining multiple oncologic biomarkers provides better therapeutic guidance.
Conclusion
Oncologic biomarkers are transforming oncology by guiding diagnosis, treatment, and follow-up. From mutations such as EGFR and BRAF to circulating biomarkers like ctDNA and protein markers such as HER2 and PD-L1, their role is central in personalized medicine and clinical research. Correct selection and interpretation of oncologic biomarkers improves outcomes and optimizes the development of new therapies.
