In today’s clinical practice, tumour markers have become an important component in the detection and care management of cancers. These tests are useful in screening for early malignancy through prognosis, therapeutic intervention and monitoring. However, the application of tumour markers in clinical assessment requires a critical understanding of the basics of pathophysiology, techniques of identification or testing, reasons for out-of-range levels of tumour markers, as well as the knowledge of evidence of their role in any given malignancy.
Early diagnosis in cancer care is important, even for asymptomatic patients. Early diagnosis is an offshoot of accurate diagnosis which is essential for improving patient outcomes, restoring hope in healthcare systems, and saving costs & resources. In regular health checkups, it may be difficult to detect certain tumour markers that can prompt further diagnosis, but hospitals and diagnostics centres can equip their facility with simple equipment that can both run regular blood work and check for specific biomarkers when the need arises. An example of such analysers is the Cobas C analysers by ROCHE.
Applications of Tumour Markers in Clinical Diagnosis
In clinical diagnosis, elevated levels of tumour markers are not enough indicators for a specific diagnosis but a call for an aggressive investigative approach. Placing simple clinical chemistry analysers that can detect general abnormal values in serum analysis can give primary healthcare providers a direction with helping patients access help before a simple situation gets out of hand. It can also help to monitor response to therapy upon diagnosis and treatment.
Of course, it is required that the healthcare provider understand the reasons for out-of-range levels of tumour markers, as well as have knowledge of evidence of their role in any given malignancy. While a single test is not enough to establish a diagnosis or initiate treatment, here are some markers that can be detected on the cobas c systems, which can lead to further diagnosis.
- LDHI2 (Lactate Dehydrogenase acc. to IFCC ver.2)
LDHI2 is a Roche in vitro test for the quantitative determination of lactate dehydrogenase (LDH) in human serum and plasma on Roche/Hitachi cobas c systems.
Lactate Dehydrogenase (LDH), found in almost all body tissues, is an enzyme that catalyses the reversible conversion of lactate to pyruvate thereby reducing NAD+ to NADH and vice versa. In certain conditions like liver disease, anaemia, muscle trauma, cancers, HIV infection, etc., this enzyme may become elevated in the blood. It is also a non-specific marker of tissue turnover, a normal metabolic process.
Haemolysis affects the activity of LDH because red blood cells (RBCs) contain their own LDH protein. During haemolysis there is an artifactual increase in LDH leading to false-positive high results.
While all these limitations exist, in cancer diagnosis, the highest levels of LDH are reported in disseminated carcinoma and mild increases in leukaemia. Likewise, many cancers can cause a general increase in LDH levels or in one of its isozymes. This means that LDH provides incomplete information and cannot be used to identify the specific cancer. Further assays are usually required for complete information and accurate diagnosis.
- ALTL (Alanine aminotransferase acc. IFCC with or without pyridoxal phosphate activation)
ALTL is the in vitro test for the quantitative determination of alanine aminotransferase (ALT), with or without pyridoxal phosphate activation, in human serum and plasma on the cobas c 111 system.
Alanine aminotransferase (ALT) is also reported to be present in a variety of tissues but is majorly found in the liver. As a result, elevated serum ALT is used to diagnose liver problems including liver cancer. There are several other indications for elevated ALT which make single test diagnosis insufficient. Additional assays will be required to reach a more conclusive diagnosis.
- ASTL (Aspartate Aminotransferase)
ASTL is the in vitro test for the quantitative determination of aspartate aminotransferase (AST), with or without pyridoxal phosphate activation, in human serum and plasma on cobas c 111 systems.
Aspartate aminotransferase (AST) enzyme is mostly found in the hepatic, cardiac, muscle, and kidney tissues. Elevated levels of AST may indicate metastatic carcinoma, particularly when it spreads to the liver and invades the hepatic tissue, among other liver problems.
Cancer diagnosis may not be confirmed in isolation, but in combination with other assays and imaging studies.
- AMYL2 (α-Amylase EPS ver.2)
AMYL2 is the in vitro test for the quantitative determination of α‑amylase in human serum, plasma and urine on cobas c systems.
The α‑amylases (1,4‑α‑D‑glucanohydrolases, EC 3.2.1.1) catalyse the hydrolytic degradation of polymeric carbohydrates such as amylose, amylopectin and glycogen by cleaving 1,4‑α‑glucosidic bonds. α‑amylases can be classified in two – the pancreatic (P-type) and salivary (S-type). The P-type is almost exclusively associated with the pancreas while the S-type can be associated with different sites such as in tears, sweat, human milk, amniotic fluid, the lungs, testes and the epithelium of the fallopian tube.
α-amylase determinations are useful in the diagnosis and monitoring of acute pancreatitis. However, they can also be used to detect tumours of the lungs or ovaries, renal failure, diabetic ketoacidosis, and other issues.
- LIPC (Lipase colorimetric assay)
LIPC is the enzymatic in vitro test for the quantitative determination of lipase in human serum and plasma on cobas c systems.
Pancreatic lipase analysis in human serum and plasma are useful for the differential diagnosis and monitoring of various pancreatic conditions, in addition to α-amylase. Human pancreatic lipase is a glycoprotein, with a molecular weight of 45‑48 kDa, secreted into the duodenum through the duct system of the pancreas. The concentration in blood is normally very low – concentration gradient between pancreatic tissue and serum lipase is approximately 20,000‑fold. When injured, the pancreas starts to release the lipase into blood at higher amounts. Conditions that can result in elevated pancreatic lipase include acute pancreatitis, chronic pancreatitis, pancreatic cancer, or pancreatic duct obstruction.
To achieve more accurate diagnosis, clinical interpretation of lipase levels should be done in conjunction with a comprehensive assessment of the patient’s medical history, symptoms, and other diagnostic tests.
In Summary
Clinical analysis of tumour markers is not sufficient in the diagnosis of cancer, but it can serve an important role in early diagnosis when used in conjunction with patient’s medical history, symptoms, and other diagnostic tests. In places with limited access to high level medical care systems, proper analysis of general tumour markers may help healthcare providers and their patients initiative aggressive investigations that can lead to early diagnosis, accurate therapeutic interventions, and proper disease monitoring. This can save health systems the burden of wrong diagnosis and waste of resources while providing patients with long term relief to their ailment.
Speak with a specialist if you are setting up a clinical laboratory or upgrading an existing one.