Tumour Markers

Alpha-fetoprotein (AFP) is a 591 amino acid glycoprotein produced by the liver and yolk sac of a developing baby during pregnancy. Plasma concentrations begin decreasing at the end of the first trimester of pregnancy and fall rapidly after birth, with normal adult concentrations achieved by the age of 8 to 12 months. AFP is increased in neonates, during pregnancy and in some patients with benign liver disease. AFP is usually measured to assist with diagnosis of primary hepatocellular carcinoma or non seminomatous germ cell tumour (NSGCT) and to monitor treatment or detect recurrent disease in patients with these tumours. N.B. Send AFP for maternal screening to Medical Genetics, QEUH.

Sample Requirements and Reference Ranges

• Sample Type: Serum
• Container: SST
• Precautions: None
• Minimum Volume: 2 mL
• Reference Range: ≤6 kU/L
• Turnaround Time: 1 day
• Method: Abbott Architect/Alinity
• Quality Assurance: UK NEQAS

CA125 (carbohydrate antigen 125) is a glycoprotein MW >200 kDa. It is present in tissues derived from the foetal coelomic epithelium. In adults it occurs on the pleura and peritoneum, the gastrointestinal tract and female reproductive tract, including the endometrium. CA125 may be increased in women at the time of menstruation, in endometriosis, benign ovarian disease and renal or liver disease, and may be very high in early pregnancy. It is also elevated in patients with ascites, a pleural effusion or CCF.  Measurement is usually restricted to monitoring the treatment of ovarian carcinoma. 

Sample Requirements and Reference Ranges

• Sample Type: Serum
• Container: SST
• Precautions: None
• Minimum Volume: 2 mL
• Reference Range: ≤35 kU/L
• Turnaround Time: 1 day
• Method: Abbott Architect/Alinity
• Quality Assurance: UK NEQAS

Calcitonin is a 32 amino acid peptide synthesised, stored and secreted by the C-cells of the thyroid. Measurement of calcitonin is useful in the diagnosis and monitoring of medullary thyroid carcinoma (MTC), a rare tumour, accounting for only 10% of all thyroid carcinomas. MTC can occur as a sporadic tumour or inherited as part of multiple endocrine neoplasia type 2 (MEN 2). C-cell hyperplasia can increase calcitonin concentration and response to calcium infusion can be used to distinguish hyperplasia from MTC. NB. Calcitonin is only useful as a screening test in patients where there is a known family history of MTC.

Sample Requirements and Reference Ranges

• Sample Type: Plasma
• Container: Lithium heparin
• Precautions: Separate and freeze plasma within 4 hours of sample collection. Transport frozen.
• Minimum Volume: 1 mL
• Reference Range: <9 ng/L
• Turnaround Time: 14 days
• Method: Siemens Immulite
• Quality Assurance: UK NEQAS

Carcinoembryonic antigen (CEA) is a highly glycosylated cell surface glycoprotein involved in intercellular adhesion. Its size varies in different organs from 90 to 200 kDa, due to variable glycosylation. CEA may be elevated in smokers and a number of benign liver, renal, lung or gastrointestinal tract conditions. Therefore CEA is not a useful screening or diagnostic test. Its main role is to monitor response to therapy and detect recurrent gastrointestinal malignancy.

Sample Requirements and Reference Ranges

• Sample Type: Serum
• Container: SST
• Precautions: None
• Minimum Volume: 2mL
• Reference Range: ≤5 μg/L
• Turnaround Time: 1 day
• Method: Abbott Architect/Alinity
• Quality Assurance: UK NEQAS

Chromogranin A is an acidic 439 amino acid glycoprotein (48 kDa) originating from the chromaffin granules of most neuroendocrine cell types. In health, chromogranin A is released as a pro-hormone together with other peptide hormones in response to stimulation. Larger quantities of chromogranin A are produced by neuroendocrine derived tumours thus allowing it to be used as a tumour marker. Chromogranin A is the most commonly raised neuroendocrine tumour (NET) marker.

This guidance details which tumour markers to request during the diagnosis and monitoring of NETs.

Sample Requirements and Reference Ranges

• Sample Type: Serum
• Container: SST/Plain Serum
• Precautions: Spin and separate within 8 hours. Store serum for up to four days refrigerated. Store frozen if longer term storage is required. Samples from referral laboratories can be posted at room temperature using 1^st class post.
• Minimum Volume: 1 mL
• Reference Range: <95 µg/L
• Turnaround Time: 28 days
• Method: CisBio ELISA
• Quality Assurance: UK NEQAS

Gastrin-secreting cells (G-cells) produce, store and release gastrin within the pyloric and upper duodenal mucosa. Gastrin stimulates gastric acid secretion by parietal cells and circulates in 2 active forms: gastrin-34 (G-34) and gastrin-17 (G-17).   Determination of circulating gastrin concentrations can aid in the diagnosis of gastrinoma. Greater than 50% are malignant and approximately 25% occur as part of multiple endocrine neoplasia type 1 (MEN 1). The presence of gastrinoma and hypergastrinaemia resulting in severe refractory peptic ulcer disease is known as Zollinger-Ellison syndrome. Increased circulating gastrin concentrations can also occur as a result of reduced or absent gastric acid secretion e.g. H pylori infection, chronic atrophic gastritis +/- pernicious anaemia or long-term use of proton pump inhibitors (PPIs). This is due to the lack of inhibitory feedback of acid on the G-cells. Therefore elevated gastrin levels should be interpreted in relation to gastric acid secretion.

Sample Requirements and Reference Ranges

• Sample Type: Plasma
• Container: Heparinised plasma (EDTA unsuitable)
• Precautions: Sample should be collected after an overnight fast. Separate and freeze plasma within 4 hours of sample collection. Transport frozen. Proton pump inhibitors should be discontinued for a week, and H2 blockers for 48 hours, prior to sampling. Icterus and lipaemia moderately reduce results.
• Minimum Volume: 1 mL
• Reference Range: <115 µg/L (fasting)
• Turnaround Time: 28 days
• Method: Siemens Immulite. This assay measures both the G-17 isoform and, to a lesser extent, the G-34 isoform.
• Quality Assurance: UK NEQAS

Human chorionic gonadotrophin (HCG) is a glycoprotein hormone produced by trophoblastic tissue. This is found in the placenta in normal pregnancy, in choriocarcinoma and in trophoblastic elements in germ cell tumours. HCG consists of two subunits (alpha and beta). When HCG is used as a tumour marker it is important that both free beta subunit and intact HCG are measured. HCG is used to diagnose, monitor or detect recurrent disease in germ cell tumours. 

Sample Requirements and Reference Ranges

• Sample Type: Serum
• Container: SST
• Precautions: None
• Minimum Volume: 2 mL
• Reference Range: As tumour marker ≤5 U/L
• Turnaround Time: 1 day
• Method: Abbott Architect/Alinity
• Quality Assurance: UK NEQAS

Metastatic carcinoid tumours arising from enterochromaffin cells produce excessive amounts of serotonin. The main metabolite of serotonin, 5-hydroxyindole acetic acid (5-HIAA) is excreted in urine and its measurement can be used to diagnose and monitor carcinoid tumours.

Sample Requirements and Reference Ranges

• Sample Type: 24 hr urine (acidified)
• Container: 24 hr urine container with 50 mL hydrochloric acid
• Precautions: Elevated by dietary walnuts, bananas, tomatoes, avocado, kiwi fruit,  pineapple, plantain, plums, pecan nuts. Avoid for 3-4 days prior to  starting urine collection. Patient information sheet for urine collection

• Minimum Volume: 10 mL
• Reference Range: ≤ 42 μmol/24 h
• Turnaround Time: 14 days
• Method: Liquid chromatography-tandem mass spectrometry
• Quality Assurance: UK NEQAS

The plasma free metadrenalines profile:

• Metadrenaline
• Normetadrenaline
• 3-methoxytyramine

Plasma free metadrenalines are used for the diagnosis of catecholamine producing tumours including phaeochromocytoma or paraganglioma (PPGL). Patients with PPGL may present with episodes of hypertension with palpitations, severe headaches and sweating. Patients may be asymptomatic but have an incidentally discovered adrenal mass.

Sample Requirements and Reference Ranges

• Sample Type: Plasma
• Container: EDTA
• Precautions: Plasma must be separated from red blood cells within 2 hours of collection. Certain medications may cause false elevations of plasma metadrenalines. If clinically feasible, it is optimal to discontinue these medications at least 1 week before sample collection.
• Minimum Volume: 500 µL
• Reference Range:
  • Metadrenaline < 510 pmol/L
  • Normetadrenaline < 1180 pmol/L
  • 3-methoxytyramine < 180 pmol/L
• Turnaround Time: 14 days
• Method: Liquid chromatography-tandem mass spectrometry
• Quality Assurance: UKNEQAS

The urine free metadrenaline profile:

• Metadrenaline
• Normetadrenaline
• 3-methoxytyramine

Urine free metadrenalines are used for the diagnosis of catecholamine producing tumours including phaeochromocytoma or paraganglioma (PPGL). Patients with PPGL may present with episodes of hypertension with palpitations, severe headaches and sweating. Patients may be asymptomatic but have an incidentally discovered adrenal mass.

Sample Requirements and Reference Ranges

• Sample Type: 24hr urine
• Container: Plain urine container (no preservative)
• Precautions: Certain medications may cause false elevations of urine metadrenalines. If clinically feasible, it is optimal to discontinue these medications at least 1 week before sample collection. Patient information sheet for urine collection

• Minimum Volume: 10 mL
• Reference Range:
  • Metadrenaline < 350 nmol/24 h
  • Normetadrenaline < 650 nmol/24 h
  • 3-methoxytyramine < 400 nmol/24 h
• Turnaround Time: 14 days
• Method: Liquid chromatography-tandem mass spectrometry
• Quality Assurance: RCPA

Prostate specific antigen (PSA), a protease, is a normal constituent of seminal fluid. It is produced by the secretory cells of the acini and ducts of the prostate and other cells expressing the nuclear androgen receptor.  PSA is measured to aid the diagnosis and for monitoring of prostate cancer.   PSA may be spuriously elevated in a number of situations: catheterisation; acute retention of urine; urinary infection; ejaculation or vigorous exercise; DRE; prostate biopsy. Where these may have contributed to an elevated PSA result, suggest repeat in 6 weeks.

Sample Requirements and Reference Ranges

• Sample Type: Serum
• Container: SST
• Precautions: None
• Minimum Volume: 2 mL
• Reference Range:
  •  Age (yrs)          PSA (μg/L)
  • <60                      ≤ 3.0
  • 60 – 69                 ≤ 4.0
  • ≥70                      ≤ 5.0
• Turnaround Time: 1 day
• Method: Abbott Architect/Alinity
• Quality Assurance: UK NEQAS

Thyroglobulin (Tg), a protein produced by normal or malignant thyroid tissue, is used to monitor treatment of differentiated thyroid cancer and to detect recurrence. Tg measured a few months after total thyroidectomy for thyroid carcinoma provides valuable prognostic information. Please note that recent thyroid biopsy or surgery will cause an increase in Tg. 15-20% of thyroid cancer patients have thyroglobulin antibodies (TgAb). If present, TgAb can interfere with Tg measurements causing an artefactually low result. TgAb status may alter during treatment and TgAb should therefore always be measured on all Tg samples. Persistent or increasing concentrations of TgAb following thyroidectomy may indicate residual or recurrent tumour. Tg measurement is also of use in establishing the presence or absence of thyroid tissue in neonates with congenital hypothyroidism.

Sample Requirements and Reference Ranges

• Sample Type: Serum
• Container: Plain/SST
• Precautions: None
• Minimum Volume: 2 mL
• Reference Range: Not applicable
• Turnaround Time: 7 days
• Method: Beckman Access
• Quality Assurance: UK NEQAS