Is there genetic testing for lung cancer?
Non-small cell lung cancer (NSCLC) develops when certain cells mutate in a person’s lungs. By testing for specific genetic mutations, doctors can individualize a person’s treatment. Because some people may be more resistant to certain treatments than others, genetic testing can greatly improve the outlook for people with NSCLC.
Genetic testing for non-small cell lung cancer (NSCLC)
Lung cancers begin in the lungs, but they can spread to other parts of the body. Doctors classify lung cancer types according to the size and shape of the cancer cells seen under a microscope. Around 13%Trusted Source of lung cancers are small-cell lung cancers (SCLC) and 84% are non-small cell lung cancers (NSCLC).
NSCLC is an umbrella term that includes several subsets, like adenocarcinoma, squamous cell, and large cell carcinoma.
Many people receive a diagnosis of NSCLC after it has spread to other parts of their body. Changes in the DNA of the tumor cells can make the cancer spread faster. By gaining a better understanding of the DNA in these mutations, doctors can identify the most effective treatment for a person.
According to the Lung Cancer Foundation of America, everyone with a lung cancer diagnosis should undergo this type of biomarker testing.
This article will look at the genetic mutations that are most common among people with NSCLC. It will also look at genetic testing for these mutations, and at how these mutations influence a person’s treatment choices.
What are genetic mutations?
The human body is made up of millions of cells, and different kinds of cells have different functions. Human cells are constantly dying, dividing, and growing. The genes within a person’s cells control this process of cellular development.
Genes act a little like instruction manuals for the body to follow to produce new cell matter. Genetic mutations are changes within the genes. These mutations can alter the instructions that regulate cell death, division, and growth.
Some genetic mutations can make cells develop in uncontrolled and unusual ways. These mutations lead to the growth of tumors, some of which can be cancerous.
Genetic mutations are a natural part of life, and many are harmless. However, when the cells in a person’s lungs mutate in certain ways, NSCLC can develop.
These NSCLC-causing mutations can arise randomly. However, scientists estimate that roughly 90%Trusted Source of lung cancers have links with tobacco use. Other causes include:
- alcohol use
- exposure to ionizing radiation
- exposure to radon
- exposure to asbestos
There are many different kinds of genetic mutations. When an expert tests this sample of lung tissue, they will be looking for genetic mutations which scientists know can cause NSCLC.
A 2020 study Trusted Source found a variety of NSCLC mutations, including to these genes:
Why are genetic tests so important in NSCLC treatment?
Genetic testing means that doctors can personalize treatment plans according to which mutations they identify in a person’s cells.
For example, researchers in the 2020 study Trusted Source mentioned above analyzed the genes of 256 people in China with NSCLC. They found that the most common genetic mutations among these participants were to the EGFR, ERBB2, and KRAS genes. Of the total participants, 63% had two or more mutations.
One participant had an uncommon mutation in two genes. This means one of the genes could develop a resistance to certain medications, which directed doctors to use a different type of treatment that might be more effective.
How do the mutations affect treatment?
When doctors know which genetic mutations may be causing a person’s NSCLC, they can use tyrosine kinase inhibitors (TKIs) to provide the best, most personalized treatment possible.
TKIs are drugs that can travel through the cell membrane. By stopping various genes and proteins from doing their jobs, these drugs interfere with the processes that cause cancer cells to grow and divide.
Different genetic mutations require different TKIs. Although many such drugs exist, doctors tend to use some more than others. For instance, the National Cancer Institute (NCI) lists the following common TKIs:
- EGFR inhibitors: erlotinib, gefitinib, afatinib, osimertinib, dacomitinib.
- BRAF inhibitors: dabrafinib.
- ALK inhibitors: crizotinib, entrectinib, ceritinib, alectinib, brigatinib, and lorlatinib.
- RET inhibitors: selpercatinib.
- NTRK inhibitors: larotrectinib.
- ROS1 inhibitors: crizotinib and entrectinib.
As the list indicates, some TKIs can target multiple genetic mutations. For instance, crizotinib can target ROS1 and ALK.
Other mutations have proven more resistant to existing TKIs. However, scientists are working hard to develop more effective treatment options.
For example, a 2020 studyTrusted Source from Korea reports that earlier research did not find HER2 TKIs to be very effective. However, the same study notes that some newer drugs may better target the HER2 gene. These include:
- adotrastuzumab emtansine (T-DM1)
Similarly, the National Cancer Institute (NCI) recently announced that a KRAS inhibitor known as sotorasib may reduce tumor size in people with NSCLC who have a mutation in that specific gene.
What to expect during a genetic test
According to the NCI, doctors perform genetic testing by first taking a small sample of abnormal-looking tissue from a person’s lungs. This is known as a biopsy.
Doctors do this by using a very fine needle, which sucks up the sample of lung tissue. They can locate the tissue by using imaging technology, like a CT scan, or performing a procedure known as a bronchoscopy, which is the insertion of a flexible fiberoptic scope into the patient’s airway. Sometimes the scope has an ultrasound probe at the tip to help locate cancerous tissue. The doctors then send the sample to a laboratory for testing.
Once doctors suspect that somebody’s symptoms may be NSCLC, they can use a variety of different techniques to reach a diagnosis.
Imaging techniques can helpTrusted Source doctors detect lung tumors and track their development. These can include:
- MRI scans
- CT scans
- PET scans
Doctors can also use laboratory tests to look for cancer cells. For example, in sputum cytology, a doctor investigates a sample of mucus that their patient has coughed up.
Other laboratory tests require more invasive procedures to collect a sample for testing. For instance, doctors may test lung tissue for cancer cells, which involves performing a lung biopsy. Doctors may also need to investigate the fluid between a person’s chest and lungs.
Signs and symptoms of NSCLC
As a 2020 overview Trusted Source explains, lung cancer typically presents with the following symptoms:
- a prolonged cough, which may recur
- coughing up blood
- shortness of breath
In rare cases, lung cancer can also cause shoulder pain, hand muscle atrophy, and Horner syndrome, a disruption of the nerves that control a person’s eyes and face.
Doctors can sometimes mistake lung cancer for conditions that have similar symptoms. These include:
It is also possible for someone’s lung cancer to develop in a symptomless way, at least in the early stages. Indeed, a 2019 article Trusted Source notes that most lung cancer diagnoses occur during the more advanced stages of the disease.