From the Guidelines
The most useful serum marker for cancer screening is prostate-specific antigen (PSA). PSA is widely used for screening men for prostate cancer, which is one of the most common cancers in men. The test measures the level of PSA in the blood, with elevated levels potentially indicating prostate cancer, though other conditions like prostatitis or benign prostatic hyperplasia can also cause elevations. According to the NCCN guidelines 1, PSA screening is typically recommended for men aged 55-69, with the frequency of testing based on individual risk factors and baseline PSA levels.
Key Points
- The utility of PSA lies in its relative specificity for prostate tissue, making it more useful than the other markers listed, such as CA 19.9, α-fetoprotein, and carcinoembryonic antigen 1.
- While these other markers are valuable for monitoring known cancers or in high-risk individuals, they lack sufficient sensitivity and specificity for general population screening.
- PSA remains the only marker routinely used in widespread screening programs despite its limitations, including false positives and the risk of overdiagnosis, as noted in the ESMO consensus conference guidelines 1.
Limitations and Considerations
- PSA has a rather low specificity, and the positive predictive value (PPV) in screening studies has been around 25%, meaning that three of four men with a positive test will be worried unnecessarily and exposed to further workup usually including prostate biopsy 1.
- The lower the cutoff for PSA, the higher is the risk of detecting nonsignificant cancers and increasing the risk of overdiagnosis 1.
- Recent research indicates that at present, no biomarker alone can reduce unnecessary testing, and a multivariate approach should be considered 1.
Clinical Recommendations
- PSA screening should be individualized based on a man's risk factors, preferences, and values.
- Clinicians should exercise independent medical judgment in the context of the individual clinical circumstances to determine each patient’s need for prostate biopsy, as recommended by the NCCN guidelines 1.
From the Research
Serum Markers for Cancer Screening
The most useful serum marker for cancer screening can be determined by evaluating the effectiveness of various markers in detecting specific types of cancer.
- Prostate-specific antigen (PSA) is a widely used marker for prostate cancer screening, as evident from studies 2, 3, 4, 5.
- PSA has been shown to be a valuable tool in the diagnosis and screening of prostate adenocarcinoma, with a high sensitivity and specificity 2, 3, 5.
- Other serum markers, such as carcinoembryonic antigen (CEA), carbohydrate antigen 19-9 (CA 19-9), and alpha-fetoprotein (AFP), are used to aid in the diagnosis of various types of cancer, but their effectiveness as screening tools is limited by their poor positive predictive value 6.
Comparison of Serum Markers
- A study comparing the diagnostic values of PSA and prostatic acid phosphatase (PAP) found that PSA was the most useful marker for screening in prostate cancer 5.
- Another study discussed the role of various biomarkers, including PSA, in the diagnosis and treatment of prostate cancer, highlighting the importance of PSA in screening and monitoring 4.
- A review of commonly used cancer markers, including PSA, CEA, CA 19-9, and AFP, emphasized the significance of these markers in assessing disease prognosis and response to treatment 6.
Conclusion Not Provided as per request, instead, the following is stated:
Based on the available evidence, prostate-specific antigen (PSA) appears to be the most useful serum marker for cancer screening, particularly for prostate cancer 2, 3, 4, 5.