Tumour Markers

Question 1

What are tumour markers used for?

Answer 1

SCREENING
-Not considered appropriate for screening the general population
-Appropriate in some high risk groups eg alpha-FP to detect hepatocellular carcinoma in patients with cirrhosis caused by chronic viral hepatitis)
DIAGNOSIS
-Most are elevated in a range of malignancies
-Some are also raised in benign conditions
-Some are raised in individuals that have a constantly abnormally high level
-Degree of elevation in some can give an indication of what malignancy is present
PROGNOSIS
-Can determine outcome, especially when assessing rate of decline post-operatively
RESPONSE
-Rate of reduction can indicate response
RELAPSE
-Elevation in patients with previously high levels can indicate relapse, but this is not always the case so over-reliance on this is not advised

Question 2

What is CEA and what cases is it seen in?

Answer 2

-A cell-surface antigen
-Expressed in many normal tissues and a wide variety of tumours
-Commonly used in cases of colorectal carcinoma
-4% elevation in Dukes’ stage A, 65% stage D)
-Elevated (>5ng/ml) levels seen in smokers, those with IBD, hepatitis, pancreatitis, gastritis

Question 3

What is CA125 and what cases is it seen in?

Answer 3

-Expressed on the surface of ovarian cells, used as a marker in ovarian carcinoma
-Elevated in: 1% of general population / 6% of those with benign conditions / 82% of those with ovarian cancer
-More severe elevation seen in ovarian cancer patients
-Also elevated in pancreatic, lung, colorectal and breast cancers

Question 4

What is Alpha-Fetoprotein and what cases is it seen in?

Answer 4

-Glycoprotein produced by a normal foetal yolk sac, liver and intestines
-Normally undetectable after the age of 1
-Moderately elevated in hepatitis but high levels are seen in hepatocellular carcinoma and cancers containing yolk sac elements eg teratomas
-High levels predict a poor prognosis

Question 5

What is HCG and what cases is it seen in?

Answer 5

-Human Chorionic Gonadotrophin (glycoprotein)
-Elevated in patients with gestational trophoblastic disease (choriocarcinoma)
-Specific elevation of the beta-subunit in patients with non-seminomatous testicular cancers

Question 6

What is PSA and what cases is it seen in?

Answer 6

-Prostate Specific Antigen
-Raised levels in prostate cancer and BPH (ubiquitous in ageing men)
-DRE, prostatitis and UTIs also cause raised levels
-Used to monitor response to hormonal and cytotoxic treatments and after radical treatment
-Lacks sufficient sensitivity and specificity to be used as a screening test alone

Question 7

What are immunoglobulins an what cases are they seen in?

Answer 7

-Can measure / monitor paraproteinaemias eg myeloma and sometimes non-Hodgkin’s lymphoma
-Can be measured in the blood or in the urine