Cancer Blood Tests: Comprehensive Overview and Latest Technologies
This article introduces the uses of blood tests for cancer patients, covering traditional tumor markers, pre-chemotherapy testing, and the latest circulating tumor cells (CTC) and liquid slide technology, helping patients understand the importance of tracking and precision medicine.
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Blood tests are an essential part of cancer treatment and monitoring. In Hong Kong, doctors routinely order blood tests during chemotherapy, targeted therapy, immunotherapy, or follow-up periods to assess the patient’s health, immune function, organ function, and tumor changes.
1. Do Healthy People Need Blood Tests Before Diagnosis?
Early cancer screening in Hong Kong primarily relies on imaging and specialized tests, such as mammography, colonoscopy, Pap smears, and low-dose CT scans. Blood tests alone are not recommended for cancer screening, as elevated tumor markers (CEA, CA19-9, CA125, etc.) do not always indicate cancer, and normal values do not guarantee absence of disease.
2. Blood Tests Before and During Chemotherapy
Before chemotherapy, doctors check complete blood counts (white blood cells, red blood cells, platelets) to ensure immune and bone marrow function. Low white blood cells may delay treatment or require growth factors. Kidney function (creatinine), liver function (AST/ALT), and protein levels (albumin) are also assessed to confirm that patients can tolerate treatment.
3. Purpose of Tumor Markers
While not suitable for initial screening, tumor markers are valuable for monitoring. For patients with colorectal, breast, or ovarian cancer, rising tumor markers may indicate recurrence or metastasis and should be confirmed with imaging.
4. Blood Tests During Targeted and Immunotherapy
Although targeted and immunotherapies are precise, they can still affect the liver, kidneys, or immune system. Regular blood tests help detect side effects early.
5. Circulating Tumor Cells (CTCs) and Liquid Biopsy
New medical technologies allow detection of circulating tumor cells (CTCs) via blood tests. These cells, shed from tumors into the bloodstream, can:
- Predict recurrence risk, often 6 months earlier than imaging
- Analyze cancer stem cell markers
- Assess chemosensitivity
- Test sensitivity to natural substances
CTC analysis provides a basis for personalized treatment, enabling true precision medicine.
6. Other Blood Biomarkers
Beyond traditional measures like blood sugar and cholesterol, recent studies highlight links between vitamin D levels, inflammatory markers (CRP, N/L ratio), and cancer recurrence. Monitoring these markers may support immunity and reduce recurrence risk.
Conclusion
Cancer blood tests are more than auxiliary tools—they complement imaging to provide a comprehensive monitoring approach. From traditional tumor markers to cutting-edge CTC and liquid biopsy technologies, blood testing is enhancing precision and personalized care for cancer patients in Hong Kong.
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References
- Hanahan, D., & Weinberg, R. A. (2011). Hallmarks of cancer: The next generation. Cell, 144(5), 646–674.
- Alix-Panabières, C., & Pantel, K. (2014). Challenges in circulating tumour cell research. Nature Reviews Cancer, 14(9), 623–631.
- Pantel, K., & Alix-Panabières, C. (2019). Liquid biopsy and minimal residual disease — latest advances and implications for cure. Nature Reviews Clinical Oncology, 16(7), 409–424.