What are the common tumor markers checked in blood work?

Common Tumor Markers in Blood Work

The most commonly used tumor markers in blood work include CA 15-3, CA 27.29, CEA, AFP, β-HCG, LDH, CA 19-9, CA-125, and PSA, each with specific applications for different cancer types. These markers are primarily useful for monitoring treatment response and detecting recurrence rather than for initial cancer screening or diagnosis.

Breast Cancer Markers

• CA 15-3 and CA 27.29: These are MUC-1 antigen-based markers primarily used for monitoring treatment response in metastatic breast cancer 1

  • Not recommended for screening, diagnosis, or staging
  • Can be used to monitor response to therapy in metastatic disease
  • Not recommended for routine surveillance after primary therapy

• CEA (Carcinoembryonic Antigen): Often used alongside CA 15-3/CA 27.29 in breast cancer monitoring 1

Testicular Cancer Markers

• AFP (Alpha-fetoprotein): Elevated in nonseminomatous germ cell tumors 1

  • Normal in pure seminoma
  • Elevated AFP with seminoma histology indicates mixed germ cell tumor

• β-HCG (Beta-human chorionic gonadotropin): May be elevated in both seminomatous and nonseminomatous tumors 1

  • Half-life of approximately 1-3 days
  • Caution needed as hypogonadism and marijuana use may cause benign elevations

• LDH (Lactate dehydrogenase): Used for staging and prognosis in testicular cancer 1

Gastrointestinal Cancer Markers

• CEA: Primary marker for colorectal cancer monitoring 2

  • Used to detect relapse after treatment
  • Elevated in approximately 30% of cholangiocarcinoma patients 1

• CA 19-9: Primary marker for pancreatic cancer and biliary tract malignancies 1, 2

  • Elevated in up to 85% of patients with cholangiocarcinoma
  • A value greater than 100 U/ml has a sensitivity of 75% and specificity of 80% in patients with PSC
  • Can be elevated in non-malignant obstructive jaundice

Gynecological Cancer Markers

• CA-125: Primary marker for ovarian cancer 1, 2
  • Useful for evaluating pelvic masses in postmenopausal women
  • Used for monitoring response to therapy in ovarian cancer
  • Elevated in 40-50% of cholangiocarcinoma patients

Liver Cancer Markers

• AFP: Primary marker for hepatocellular carcinoma 2
  • Used for screening high-risk populations
  • Helps assess hepatic masses in patients at risk for liver cancer

Prostate Cancer Markers

• PSA (Prostate-specific antigen): Used for prostate cancer screening, detecting recurrence, and monitoring treatment response 2

Clinical Applications and Limitations

Appropriate Uses:

• Monitoring treatment response: Most established use of tumor markers 3
• Detecting recurrence: Rising levels may detect "biochemical recurrence" before clinical or radiological evidence 3
• Prognosis assessment: Some markers correlate with disease burden and outcome 3

Inappropriate Uses:

• Screening general population: Most markers lack sufficient sensitivity and specificity 2
• Sole diagnostic tool: Diagnosis should not rest solely on tumor marker measurements 1

Important Considerations:

• Sampling timing: Ideally repeated after 5-6 half-lives of the marker 3
• Trend interpretation: Rising trends more significant than single elevated values 3
• Non-malignant elevations: Many markers can be elevated in benign conditions 1, 2
• Combination testing: Using multiple markers may improve diagnostic accuracy when diagnostic doubt exists 1

Pitfalls to Avoid

• Relying on a single marker measurement for diagnosis
• Using markers with poor sensitivity/specificity for screening
• Ignoring benign causes of marker elevation
• Failing to consider the entire clinical context when interpreting results
• Using markers that haven't been validated for specific clinical scenarios

Remember that no ideal tumor marker exists, and their clinical utility varies significantly depending on the specific cancer type and clinical scenario 3, 4.