From the Guidelines
Tumor markers play a valuable but limited role in cancer diagnosis and monitoring, and are most useful for monitoring treatment response, detecting cancer recurrence, and assessing prognosis rather than for initial diagnosis. The use of tumor markers in cancer management is guided by evidence-based recommendations, such as those provided by the American Society of Clinical Oncology (ASCO) 1. For example, CEA is recommended for monitoring patients with metastatic colorectal cancer during active therapy, while CA 15-3 and CA 27.29 are not recommended for screening, diagnosis, or staging of breast cancer 1.
Some key points to consider when using tumor markers include:
- Tumor markers often lack specificity and sensitivity, and may be elevated in non-cancerous conditions or not elevated in all cancer cases 1
- Tumor markers are typically measured through blood tests at regular intervals during and after cancer treatment 1
- The clinical utility of tumor markers varies significantly depending on the specific marker and cancer type, with some providing more reliable information than others 1
- Physicians typically establish a baseline level before treatment and then monitor trends over time, as the pattern of change often provides more valuable information than any single measurement 1
In terms of specific tumor markers, PSA is widely used for monitoring prostate cancer, while CA-125 is commonly used for ovarian cancer 1. CEA is used for colorectal cancer, AFP for liver cancer, and CA 19-9 for pancreatic cancer 1. However, the use of these markers is not without limitations, and they should be used in conjunction with other diagnostic tools, such as imaging studies and biopsies 1.
Overall, the use of tumor markers in cancer management should be guided by evidence-based recommendations and individualized to each patient's specific needs and circumstances 1.
From the Research
Role of Tumour Markers in Cancer Diagnosis and Monitoring
- Tumour markers are used in various aspects of cancer care, including screening, diagnosis, prognosis, and monitoring of treatment response and disease recurrence 2, 3, 4, 5, 6
- These markers can be detected in tissue or body fluids such as ascitic or pleural fluid or serum, and their clinical uses can be broadly classified into four groups: screening and early detection, diagnostic confirmation, prognosis and prediction of therapeutic response, and monitoring disease and recurrence 2
- Ideal tumour markers do not exist, and their application in clinical practice requires a thorough understanding of the basics of pathophysiology, techniques of identification or testing, and the knowledge of evidence of their role in a given malignancy 2
Clinical Uses of Tumour Markers
- Screening and early detection: tumour markers such as carcinoembryonic antigen (CEA), alphafetoprotein (AFP), and prostate-specific antigen (PSA) can be used for screening and early detection of certain cancers 3, 4
- Diagnostic confirmation: tumour markers can aid in the diagnosis of cancer, but establishing a diagnosis based on tumour markers alone is not recommended due to the problem of nonspecificity 2, 3
- Prognosis and prediction of therapeutic response: tumour markers such as CA-125 and CA-19.9 can be used to predict the prognosis and response to therapy in patients with ovarian and pancreatic cancers, respectively 3, 4
- Monitoring disease and recurrence: tumour markers can be used to monitor disease progression and detect recurrence, with rising trends in serum levels potentially indicating recurrence before clinical or radiological evidence is apparent 2, 5
Limitations and Future Directions
- Tumour markers have limitations, including variable sensitivity and specificity, and their use should be interpreted in conjunction with diagnostic imaging, clinical history, and physical examination 5, 6
- Recent research has shown that the use of multiple tumour markers as a panel or as part of validated algorithms can improve diagnostic performance, and newer tumour markers with increased sensitivity and specificity are being discovered 6
- The future direction of tumour markers includes their integration with other diagnostic modalities and emerging serum-based biomarkers, such as circulating nucleic acids, to advance diagnostic performance and improve patient management 6