The Types of Lung Cancer Biomarker Tests
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The genetic abnormalities that cause cancer can be captured in the form of DNA, mRNA, or protein. This gives rise to a variety of methods to detect biomarkers. It can be found in various biological materials, including blood, urine, tissues, cells, and genetic material (DNA or RNA).
In the early days, when there were only a handful of biomarker tests in the market, biomarker testing was done sequentially. Hospitals or cancer centers have biomarker-testing strategies to help doctors decide which specific biomarker test(s) to order for diagnostic analysis.
Biomarker tests have later evolved to detect several biomarkers (more than one genetic mutation) in one test. With a panel of biomarkers detected, a range of targets is available for cancer treatment. Biomarker panel tests can pair detected targets with different drugs.
Nevertheless, every time a test is paired with a different drug, it requires a new clinical trial and FDA approval. FDA classifies the approved biomarker tests which match cancer patients to specific drugs or therapies as “companion diagnostic devices.”
Refer to the FDA website for the latest biomarker tests approved for marketing and therapeutic uses in the US.
The rise of liquid biopsy
Lung cancer biomarker testing is usually performed on tumor biopsy. However, there are several challenges to obtaining sufficient tissue for testing, including the tumor location and invasive biopsy techniques. If cancer has spread, the doctor may perform a biopsy from the metastatic site rather than from the lung. If there is not enough tissue for testing, a second biopsy may be scheduled.
Recent technological advances have made it possible to pick up biomarkers shed from cancer cells (lung tumors or metastatic sites) in the bloodstream. Among the approved biomarker tests above, some use blood (plasma) samples, while some use both tissue and blood samples.
Compared to tissue biopsy, taking a blood sample is
- Less invasive
- Quicker
- Has a lower risk of complications
- Can be repeated many times to monitor disease progression and drug response
For these reasons, the biomarker tests using blood samples are given the name of ‘liquid biopsy.
Comprehensive biomarker testing
It takes a whole team to decide how the removed tissue (biopsy) is used. Factors that influence how elaborate biomarker testing are:
- Size of removed tissue – must be large enough to run as many tests as possible
- Health conditions and staging – patients with limited survival time or those in critical conditions may not have time for many tests
- Tests cost
If the circumstances allow, some doctors may order comprehensive biomarker testing from the beginning to plan all treatment options. A comprehensive biomarker test provides a full genomic profile of a patient’s tumor to show if the patient can benefit from different therapies.
Next-generation sequencing can analyze many genetic and protein abnormalities associated with a patient’s lung cancer in one test. The downside of next-generation sequencing.
The level of PD-L1, a biomarker and target for lung cancer immunotherapy, can also be measured via next-generation sequencing. Alternatively, there are approved tests for PD-L1 in the market.
Staying up-to-date on the latest developments is crucial to ensure that patients can receive a comprehensive diagnosis. Fortunately, the tests have become increasingly convenient, making the process more comfortable.
