The field of oncology has evolved rapidly in the past decade, with tumor markers playing a central role in cancer detection, monitoring, and treatment personalization. While traditional markers like PSA and CA 125 remain essential, 2025 has brought new attention to genetic and molecular biomarkers such as KRAS mutations, PD-L1 expression, and circulating tumor DNA (ctDNA).
This article explores the Top 10 Tumor Markers every oncologist should know in 2025, their clinical significance, and their impact on precision oncology.
1. PSA (Prostate-Specific Antigen)
- Cancer type: Prostate cancer
- Clinical role: Screening, monitoring treatment, recurrence detection
- Why it matters in 2025: PSA remains one of the most widely used tumor markers. New refinements, including PSA density and PSA velocity, help improve specificity and reduce overdiagnosis.
2. CA 125 (Cancer Antigen 125)
- Cancer type: Ovarian cancer
- Clinical role: Monitoring therapy, detecting recurrence
- Why it matters in 2025: CA 125 is not suitable for general screening due to low specificity, but it remains essential in tracking treatment response in ovarian cancer patients.
👉 New combinations with HE4 biomarker panels improve diagnostic accuracy.
3. AFP (Alpha-Fetoprotein)
- Cancer type: Liver (HCC), testicular cancer
- Clinical role: Diagnosis, prognosis, recurrence detection
- Why it matters in 2025: AFP remains a cornerstone marker for hepatocellular carcinoma (HCC). When combined with imaging, it improves early HCC detection in high-risk patients with hepatitis or cirrhosis.
👉 In germ cell tumors, AFP provides critical diagnostic and prognostic information.
4. CEA (Carcinoembryonic Antigen)
- Cancer type: Colorectal, breast, pancreatic
- Clinical role: Monitoring after surgery, recurrence detection
- Why it matters in 2025: CEA is one of the most useful markers for colorectal cancer follow-up.
👉 Rising CEA after surgery can indicate recurrence months before imaging.
5. HER2 (Human Epidermal Growth Factor Receptor 2)
- Cancer type: Breast, gastric
- Clinical role: Predictive biomarker, guides targeted therapy
- Why it matters in 2025: HER2 testing has revolutionized breast cancer therapy. Patients with HER2-positive tumors benefit from targeted drugs such as trastuzumab, pertuzumab, and trastuzumab deruxtecan.
👉 HER2 is a predictive marker, shaping personalized therapy decisions.
6. CA 19-9 (Carbohydrate Antigen 19-9)
- Cancer type: Pancreatic and biliary tract cancers
- Clinical role: Monitoring progression, therapy response
- Why it matters in 2025: Pancreatic cancer remains one of the deadliest cancers, and CA 19-9 remains the most reliable serum marker.
👉 Not specific enough for screening, but invaluable in tracking treatment outcomes.
7. BCR-ABL (Philadelphia Chromosome)
- Cancer type: Chronic myeloid leukemia (CML)
- Clinical role: Genetic diagnostic marker, therapeutic monitoring
- Why it matters in 2025: The discovery of the BCR-ABL fusion gene has transformed leukemia treatment.
👉 Molecular monitoring of BCR-ABL levels is critical for evaluating response to tyrosine kinase inhibitors (TKIs) like imatinib and dasatinib.
8. KRAS Mutations
- Cancer type: Colorectal, pancreatic, non-small cell lung cancer (NSCLC)
- Clinical role: Predictive marker for targeted therapy
- Why it matters in 2025: KRAS mutations are among the most common oncogenic drivers.
👉 The approval of KRAS G12C inhibitors (e.g., sotorasib) has made this mutation one of the hottest biomarkers in precision oncology.
9. PD-L1 (Programmed Death-Ligand 1)
- Cancer type: NSCLC, melanoma, bladder, head & neck cancers
- Clinical role: Predictive marker for immunotherapy
- Why it matters in 2025: PD-L1 testing guides immune checkpoint inhibitor therapy (nivolumab, pembrolizumab).
👉 In the era of immuno-oncology, PD-L1 expression is critical for selecting patients who will benefit from immunotherapy.
10. ctDNA (Circulating Tumor DNA – Liquid Biopsy)
- Cancer type: Multiple cancers (pancreatic, colorectal, breast, lung, prostate)
- Clinical role: Non-invasive cancer detection, monitoring, recurrence prediction
- Why it matters in 2025: ctDNA, detected via liquid biopsy, is one of the most promising advances in cancer diagnostics.
👉 It allows real-time monitoring of tumor genetics, without invasive biopsies, making it a game-changer for personalized medicine.
Conclusion
The landscape of tumor markers in 2025 is a combination of traditional markers like PSA, CA 125, and AFP, and cutting-edge biomarkers like KRAS, PD-L1, and ctDNA.
For oncologists, staying up to date with these 10 markers is essential to:
- Improve early detection and accurate diagnosis
- Guide personalized treatment strategies
- Monitor treatment response and recurrence
- Integrate precision medicine and immunotherapy into clinical practice
As oncology continues to evolve, tumor markers will remain at the frontline of cancer care, shaping the future of diagnosis and treatment.