Critical Caveat — Read First
Tumour markers are NOT recommended as screening tests for asymptomatic people (with the exception of PSA in specific high-risk men, with informed discussion). Most tumour markers are used to: (1) Monitor known cancer for treatment response, (2) Detect recurrence after treatment, (3) Help diagnose when cancer is already suspected. A high tumour marker does NOT mean you have cancer — many benign conditions elevate them. A normal marker does NOT mean you don't have cancer.
Common Tumour Markers
| Marker | Cancer Association | Normal / Threshold | Used For |
|---|---|---|---|
| PSA (Prostate Specific Antigen) | Prostate cancer | <4 ng/mL (age-dependent); grey zone 4–10 ng/mL | Prostate cancer screening (controversial in asymptomatic men); monitoring after diagnosis/treatment |
| CA-125 | Ovarian cancer | <35 IU/mL | Monitoring ovarian cancer treatment response; NOT a good screening test (many benign conditions elevate it) |
| CEA (Carcinoembryonic Antigen) | Colorectal cancer (also lung, breast, pancreatic) | <5 ng/mL (smokers may have higher baseline) | Monitoring colorectal cancer after surgery; detecting recurrence |
| AFP (Alpha-fetoprotein) | Hepatocellular carcinoma (liver cancer); testicular germ cell tumours | <20 IU/mL | HCC monitoring in cirrhosis; testicular cancer monitoring |
| CA 19-9 | Pancreatic cancer; biliary tract cancer | <37 IU/mL | Pancreatic cancer monitoring; NOT a good screening test |
| Beta-hCG | Testicular choriocarcinoma; gestational trophoblastic disease | Undetectable in non-pregnant adults | Monitoring testicular cancer treatment; pregnancy |
| LDH (Lactate Dehydrogenase) | Lymphoma, testicular cancer (non-specific) | <250 U/L (lab-dependent) | Lymphoma staging and monitoring; elevated in many conditions |
Benign Causes That Elevate Tumour Markers
| Marker | Common Benign Causes of Elevation |
|---|---|
| PSA | Benign prostatic hyperplasia (BPH), prostatitis, urinary catheter, recent ejaculation, prostate biopsy, vigorous exercise (cycling) |
| CA-125 | Endometriosis, fibroids, ovarian cysts, PID, pregnancy, menstruation, liver disease, heart failure |
| CEA | Smoking, liver disease, pancreatitis, inflammatory bowel disease, pneumonia |
| AFP | Hepatitis, cirrhosis, pregnancy |
| CA 19-9 | Pancreatitis, bile duct stones, liver disease, inflammatory bowel disease |
Evidence-Based Cancer Screening (Not Blood Tests)
- Breast cancer: Mammogram every 2 years, women 40–74 (recommendations vary by country and guideline)
- Colorectal cancer: Colonoscopy from age 45–50; faecal occult blood test (FOBT) annually; faecal immunochemical test (FIT)
- Cervical cancer: Pap smear every 3 years from age 21; HPV test from age 25–30
- Lung cancer: Low-dose CT scan annually in heavy smokers (age 50–80, >20 pack-years) in some guidelines
- Prostate cancer: PSA with informed shared decision-making in men 55–69 with >10-year life expectancy
Questions to Ask Your Doctor
- Why is this tumour marker being ordered — is it for monitoring or diagnosis?
- If the marker is elevated, what are the next steps?
- Could this elevation be from a benign cause?
- What evidence-based cancer screening should I be having based on my age and sex?
- If I have a family history of cancer, does this change what screening I need?
Medical Disclaimer: This information is for educational purposes only. Cancer screening decisions should be made in consultation with a qualified doctor, taking into account individual risk factors, age, and current evidence-based guidelines.