Genetics of Lung Cancer and How to Test Them
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Cancer is a genetic disease in which cells function abnormally and grow uncontrollably due to gene changes. In some cases, these genetic abnormalities may be passed down within the family. However, it is crucial to note that many people with lung cancer have acquired various genetic mutations throughout their lives due to exposure to different environmental factors. This adds to the complexity of this disease. Fortunately, the advancement of cancer research has contributed to the various methods of identifying and detecting these genetic abnormalities that aid in diagnostic procedures.
The genetic abnormalities specific to lung cancer are called lung cancer biomarkers or tumor markers. The tests to detect the presence of these markers are known by different names, like
- Biomarker testing
- Genomic assay
- Tumor testing
- Molecular profiling
- Genetic profiling
For early-stage cancer patients, there are other treatment options for these patients with the purpose of cure. These include surgical removal of localized tumors or chemotherapy to shrink tumors, followed by radiotherapy to remove tumors. It is best to be equipped with information on biomarker testing as soon as the patient first being diagnosed with lung cancer.
Guidelines from the National Comprehensive Cancer Network (NCCN) and the College of American Pathologists recommend molecular testing for all patients with advanced or metastatic non-small cell lung cancer (NSCLC).
Broad molecular profiling (or biomarker testing) should be conducted for all advanced NSCLC subtypes:
- Adenocarcinoma
- Large cell carcinoma
- NSCLC-NOS (not otherwise specified; all other NSCLC subtypes)
- Squamous cell carcinoma (can consider molecular testing)
The broad molecular profile by NCCN NSCLC Guidelines consists of
- Driver mutations - to predict response to available targeted therapies
- PD-L1 (programmed death-ligand 1) - to predict response for immunotherapy
For targeted therapy
It is now recommended for everyone with metastatic non-small cell lung cancer (NSCLC that has spread) to have their tumor tested for biomarkers. The test helps identify the targeted therapy that specifically treats cancer-driving genetic mutation(s). Targeted therapy is a type of personalized cancer medicine as the molecular cancer profile for every patient is different. Unlike chemotherapy, which destroys all fast-growing cells, targeted therapy kills cancer cells in a precise manner.
Scientists have identified numerous genetic mutations that may lead to lung cancer. Among them, these are the most common mutations, widely recognized as lung cancer biomarkers:
For immunotherapy - PD-1 and PD-L1
One class of cancer treatment, called immunotherapy, may be recommended by doctors if
- Patients with advanced NSCLC have high expression of PD-L1 proteins
- Cancer worsens as tumor resistance develops to targeted therapy
Our immune system does not only protect us against harmful germs. It also recognizes and kills cancer cells. This video illustrates the role of the immune system in detecting cancer cells.
High levels of PD-L1 cell surface protein help cancer tumors hide from the immune system. PD-L1 testing provides the percentage of PD-L1 on cancer cells:
- High: at least half of the cancer cells have PD-L1 (≥50%)
- Low: less than half of the cancer cells have PD-L1 (1-49%)
- No PD-L1: less than 1% of the cancer cells have PD-L1
Currently, several genetic tests are available in the market for molecular profiling. The diverse functionalities of each test can be quite complicated at first glance. Read about them online and seek guidance from a healthcare expert to gain a deeper understanding of the different testing methods. This take-charge attitude can offer hope and solace throughout their journey.
Read next: Immunotherapy for Lung Cancer
