Medicine – Tumour Markers

Tumour markers are substances produced either by tumour cells or by the body in response to malignancy. They may be detected in the blood, urine or tissues and can help with diagnosis, prognosis, monitoring treatment response and detecting recurrence.

However, an important principle is:

Tumour markers are usually not specific enough to diagnose cancer on their own.

Many can also be elevated in:

Benign disease.

Inflammation.

Pregnancy.

Liver disease.

Therefore they must always be interpreted together with the clinical picture, imaging and histology where appropriate.

1. Alpha-Fetoprotein – AFP

Alpha-fetoprotein – AFP is normally produced during fetal development, particularly by the:

Fetal liver and yolk sac.

After birth, serum AFP concentrations normally fall to very low levels.

AFP and Hepatocellular Carcinoma

AFP may be elevated in:

Hepatocellular carcinoma – HCC.

It can therefore be used as a supportive marker in patients with suspected liver malignancy.

However:

A normal AFP does not exclude HCC.

Some hepatocellular carcinomas do not produce significant AFP.

AFP and Germ Cell Tumours

AFP may also be elevated in certain:

Germ cell tumours.

It is particularly associated with:

Yolk sac tumours

and tumours containing:

Embryonal carcinoma components.

Important Germ Cell Point

AFP is not elevated in a pure:

Seminoma.

Therefore:

SEMINOMA + ELEVATED AFP → THINK NON-SEMINOMATOUS COMPONENT.

This is a useful examination point.

Non-Malignant AFP Elevation

AFP can also rise in:

Pregnancy.

Chronic hepatitis.

Cirrhosis.

Liver regeneration.

Therefore an elevated AFP is not automatically diagnostic of cancer.

2. CA-125

CA-125 is most strongly associated with:

Epithelial ovarian cancer.

It is particularly useful for:

Monitoring treatment response

and

Detecting possible recurrence

in patients with known ovarian cancer.

Limitations of CA-125

CA-125 is not specific for ovarian malignancy.

It can also increase in benign conditions involving the peritoneum or reproductive tract.

Examples include:

Endometriosis.

Menstruation.

Pregnancy.

Pelvic inflammatory disease.

Benign ovarian disease.

Liver disease with ascites.

Clinical Use

Therefore:

CA-125 IS MORE USEFUL FOR MONITORING THAN FOR DIAGNOSING OVARIAN CANCER BY ITSELF.

It may also contribute to risk assessment in a patient with an:

Adnexal or ovarian mass.

3. CA 15-3

CA 15-3 is associated mainly with:

Breast cancer.

It reflects a circulating form of the:

MUC1 glycoprotein.

Clinical Use of CA 15-3

CA 15-3 is most useful in selected patients with established, particularly:

Advanced or metastatic breast cancer.

It may help assess:

Treatment response

or

Disease progression.

Limitation

CA 15-3 is not sufficiently sensitive or specific to be used as a general screening test for:

Early breast cancer.

Therefore routine breast cancer diagnosis still depends on:

Clinical examination.

Breast imaging.

Biopsy.

4. CA 19-9

CA 19-9 is associated particularly with:

Pancreatic adenocarcinoma

and

Cholangiocarcinoma.

Pancreatic Cancer

In a patient with known pancreatic cancer, CA 19-9 may help with:

Assessing disease burden.

Monitoring response to treatment.

Detecting progression or recurrence.

However, it should not be used alone to diagnose pancreatic cancer.

Cholangiocarcinoma

CA 19-9 may also be elevated in:

Bile duct cancer – cholangiocarcinoma.

Again, interpretation requires correlation with:

Imaging and clinical findings.

Benign Causes of Raised CA 19-9

CA 19-9 may also rise in benign biliary disease, particularly:

Obstructive jaundice.

Cholangitis.

Pancreatitis.

Therefore significant biliary obstruction can produce a high CA 19-9 even without malignancy.

Important Limitation

Some individuals do not express the Lewis antigen required for producing CA 19-9.

Therefore they may have:

Very low or undetectable CA 19-9

even in the presence of pancreatic cancer.

5. Carcinoembryonic Antigen – CEA

Carcinoembryonic antigen – CEA is classically associated with:

Colorectal cancer.

It is particularly useful after diagnosis and treatment.

CEA in Colorectal Cancer

CEA may be used to:

Establish a baseline level before treatment.

Monitor response to therapy.

Monitor for recurrence after treatment.

A rising CEA after colorectal cancer treatment may suggest:

Recurrent or metastatic disease.

CEA Is Not a Screening Test

CEA lacks adequate sensitivity and specificity for routine population screening.

Therefore:

CEA IS NOT USED AS A STAND-ALONE SCREENING TEST FOR COLORECTAL CANCER.

Non-Malignant Causes of Raised CEA

CEA may also be elevated in:

Smoking.

Inflammatory bowel disease.

Pancreatitis.

Chronic liver disease.

Other malignancies can also increase CEA, including some cancers of the:

Pancreas.

Stomach.

Lung.

Breast.

6. Human Chorionic Gonadotrophin – hCG

Human chorionic gonadotrophin – hCG is normally produced during pregnancy by:

Placental trophoblastic tissue.

It is also an important marker for several:

Germ cell tumours.

hCG and Germ Cell Tumours

hCG may be elevated in:

Choriocarcinoma.

Embryonal carcinoma.

Some:

Seminomas

may also produce hCG, usually through the presence of syncytiotrophoblastic cells.

hCG in Testicular Cancer

hCG is often measured together with:

AFP

and

LDH

when evaluating and monitoring:

Testicular germ cell tumours.

These markers can contribute to:

Staging.

Risk classification.

Monitoring treatment response.

Detecting recurrence.

hCG and Trophoblastic Disease

hCG is also very important in:

Gestational trophoblastic disease.

Examples include:

Hydatidiform mole

and

Gestational choriocarcinoma.

Serial hCG measurements are particularly useful for monitoring whether abnormal trophoblastic tissue persists after treatment.

7. Prostate-Specific Antigen – PSA

Prostate-specific antigen – PSA is produced by epithelial cells of the:

Prostate gland.

PSA is organ-specific but:

Not cancer-specific.

This distinction is important.

PSA and Prostate Cancer

PSA may be elevated in:

Prostate cancer.

It is used in different clinical contexts for:

Risk assessment.

Supporting investigation.

Monitoring response after treatment.

Detecting biochemical recurrence.

Benign Causes of Elevated PSA

PSA may also rise in:

Benign prostatic hyperplasia – BPH.

Prostatitis.

Urinary retention.

Some recent prostate manipulations or procedures may also affect PSA.

Therefore:

RAISED PSA ≠ PROSTATE CANCER AUTOMATICALLY.

8. AFP – Note Form

Main malignant associations:

Hepatocellular carcinoma.

Non-seminomatous germ cell tumours.

Especially yolk sac tumour.

Important point:

Pure seminoma should not produce AFP.

Non-malignant elevation:

Pregnancy.

Hepatitis.

Cirrhosis.

9. CA-125 – Note Form

Main association:

Epithelial ovarian cancer.

Main use:

Monitoring treatment and recurrence.

Can also rise in:

Endometriosis.

Pregnancy.

Menstruation.

Pelvic inflammation.

Ascites.

10. CA 15-3 – Note Form

Main association:

Breast cancer.

Main use:

Monitoring selected patients with advanced or metastatic disease.

Not suitable for:

Routine screening for early breast cancer.

11. CA 19-9 – Note Form

Main associations:

Pancreatic adenocarcinoma.

Cholangiocarcinoma.

Can also rise in:

Obstructive jaundice.

Cholangitis.

Pancreatitis.

Main use:

Monitoring established disease rather than diagnosing cancer alone.

12. CEA – Note Form

Main association:

Colorectal cancer.

Main use:

Monitoring after treatment.

Detecting possible recurrence.

Can also rise in:

Smoking.

Inflammatory bowel disease.

Pancreatitis.

Liver disease.

Other gastrointestinal malignancies.

13. hCG – Note Form

Main malignant associations:

Germ cell tumours.

Choriocarcinoma.

Gestational trophoblastic disease.

Often combined with:

AFP.

LDH.

for testicular germ cell tumours.

14. PSA – Note Form

Main association:

Prostate cancer.

Also elevated in:

Benign prostatic hyperplasia.

Prostatitis.

Urinary retention.

Important point:

PSA is:

PROSTATE-SPECIFIC BUT NOT PROSTATE-CANCER-SPECIFIC.

15. Tumour Markers Are Mainly Used for Monitoring

A major misconception is that tumour markers are primarily diagnostic tests.

In reality, many are more useful for:

Monitoring known cancer.

Assessing response to treatment.

Detecting recurrence.

Providing prognostic information.

They usually cannot replace:

Imaging

or

Histological diagnosis.

16. Tumour Markers and Screening

Most tumour markers are unsuitable for general cancer screening because benign disease can raise them and some cancers do not produce them.

For example:

CEA is not a population screening test for colorectal cancer.

CA-125 alone is not an ovarian cancer screening test for the general population.

CA 15-3 is not used to screen routinely for breast cancer.

17. Important Corrections and Clarifications

The original association:

AFP → hepatocellular carcinoma + germ cell tumours

is correct, but AFP is particularly useful for:

NON-SEMINOMATOUS GERM CELL TUMOURS.

The original:

CA-125 → ovarian cancer

is correct, but CA-125 can also rise in many benign conditions, especially:

ENDOMETRIOSIS AND PERITONEAL INFLAMMATION.

The original:

CA 15-3 → breast cancer

is correct, but its main role is:

MONITORING ESTABLISHED ADVANCED DISEASE, not screening.

The original:

CA 19-9 → pancreatic cancer/cholangiocarcinoma

is correct, but marked elevation can also occur in:

BENIGN BILIARY OBSTRUCTION.

The original:

CEA → colorectal cancer

is correct, but its strongest routine role is:

POST-TREATMENT MONITORING AND RECURRENCE SURVEILLANCE.

The original:

hCG → germ cell tumours

is correct, and it is also a major marker of:

GESTATIONAL TROPHOBLASTIC DISEASE.

The original:

PSA → prostate cancer

needs an important qualification:

PSA IS NOT CANCER-SPECIFIC.

BPH and prostatitis can also increase it.

Key Clinical Pattern

For rapid recall:

AFP → HEPATOCELLULAR CARCINOMA + NON-SEMINOMATOUS GERM CELL TUMOUR.

CA-125 → OVARIAN CANCER.

CA 15-3 → BREAST CANCER.

CA 19-9 → PANCREATIC CANCER + CHOLANGIOCARCINOMA.

CEA → COLORECTAL CANCER.

hCG → GERM CELL TUMOURS + TROPHOBLASTIC DISEASE.

PSA → PROSTATE DISEASE / PROSTATE CANCER.

And remember:

TUMOUR MARKERS SUPPORT DIAGNOSIS BUT RARELY DIAGNOSE CANCER BY THEMSELVES.

Their greatest value is usually in:

MONITORING TREATMENT RESPONSE + DETECTING RECURRENCE + ASSESSING DISEASE COURSE.