Can cancer be detected via a blood test? What do tumour markers mean?

2026-09-15

Cancer on its own can rarely be diagnosed definitively with a simple blood test, but blood tests play an essential role in raising clinical suspicion, disease monitoring, and evaluating therapeutic efficacy. Conventional and modern blood-based tests (liquid biopsy) measure molecules or cells circulating in the blood.

Tumour markers are proteins or other substances produced in higher concentrations by tumour cells or by healthy host cells in response to a malignancy. Their key features include: 1. Their significance: An elevation in their levels may suggest a malignant process (e.g., CEA in colorectal cancer, CA-125 in ovarian cancer, PSA in prostate cancer), but their increase is not exclusively associated with the presence of a neoplasm; benign lesions, inflammation, or lifestyle factors can also trigger it. 2. Limitations in general screening: Due to low specificity and low sensitivity in early-stage disease, the majority of conventional tumour markers on their own are not suitable for general public health cancer screening. 3. Primary clinical role: They are most frequently employed to monitor already confirmed malignant diseases (treatment response, recurrence, early detection of minimal residual disease). 4. Next-generation liquid biopsies: The evaluation of circulating cell-free DNA (cfDNA/ctDNA), DNA methylation patterns, circulating tumour cells (CTCs), and extracellular vesicles is an intensively researched and rapidly advancing field for early detection and therapy guidance.

In liquid biopsy research, the epigenetic patterns of circulating tumour DNA (ctDNA) (particularly DNA methylation) and multi-marker panels demonstrate superior discriminative performance compared to conventional protein markers in assessing both the presence of cancer and minimal residual disease (MRD).

References

  1. Liquid biopsy: current applications and future directions. PMID 42704556
  2. Liquid biopsy, multi-cancer early detection, and artificial intelligence: new frontiers in cancer screening from a technological and immunological perspective. PMID 42382778
  3. Recent Advances on Sensor Technologies for the Monitoring of Tumor Markers. PMID 42280221
  4. Early multi-cancer detection using liquid biopsy: emerging biomarkers and clinical strategies. PMID 42490792
  5. The Vanguard Study: Testing a New Way to Screen for Cancer NCT06995898
  6. Development of a Pan-Cancer Screening Model Based on Blood Biomarkers NCT07554157
  7. Analysis of Circulating Tumor mArkers in Blood 4 - ALCINA 4 NCT05088395

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