Researchers utilizing a population-scale biobank containing genomic data for 3.3 million participants from the USA 23andMe database have identified that lung cancer in non-smokers can rarely be the consequence of germline mutations in the EGFR gene, according to a study published by LoPiccolo et al. in the journal Science.
Population-Scale Genomic Analysis of EGFR Germline Variants
According to research published in the recent issue of Science (393, 1208), scientists completed a population-scale analysis of a rare germline variant linked to a high risk of lung cancer in individuals who do not smoke cigarettes or cigars. Veteran cancer clinician and researcher Miguel Bronchud noted via LinkedIn that the vast 23andMe database enabled researchers to study the distribution, effects, and history of the haplotype containing the T790M variant.
This large-scale biobank approach avoids the recruitment biases often found in traditional family studies or small case-control studies that enroll participants based strictly on disease status. Instead, the authors gathered data from hundreds of individuals carrying a single copy of T790M as heterozygotes. Results showed that for most carriers, the variant resided on a long, shared segment of DNA displaying the hallmarks of European ancestry, and neighboring genetic variants on this haplotype did not contribute to the effect of T790M.
Understanding EGFR Mutations and Family Risk
Epidermal growth factor receptor is a well-established oncogene featuring several common cancer-associated somatic variants that respond to targeted anticancer drugs. The gene encodes a transmembrane receptor tyrosine kinase that promotes normal cell growth. While a single mutation in a somatic cell can trigger uncontrolled proliferation, nearly all documented somatic mutations in lung cancer tissue are lethal at the embryonic stage if they occur in germ cells.
However, the T790M variant is an exception because it is not lethal during embryonic development. According to commentary from thoracic oncologists, most EGFR-positive lung cancers are not hereditary and occur through spontaneous mutations in lung cells over a lifetime. Yale School of Medicine thoracic oncologist Sarah Goldberg noted that up to 15% of non-small-cell lung cancers in the U.S. carry the EGFR mutation, with higher risk factors among Asian individuals, females, non-smokers, and people under 50. Memorial Sloan Kettering Cancer Center thoracic medical oncologist Helena Yu explained that the T790M mutation is very unusual to see in initial biomarker tests and typically appears when cancer recurs due to targeted therapy resistance.
Did you know? While T790M is notorious for causing resistance to targeted anticancer therapies in somatic cells, it can also occur as a rare germline variant in families with incomplete penetrance, meaning some individuals reach old age without developing lung cancer.
Biomarker Testing and Targeted Treatment Options
Patients diagnosed with non-small-cell lung cancer undergo biomarker testing via tumor tissue biopsies or liquid biopsies utilizing blood or body fluids. Common mutations include Exon 19 deletions and L858R point mutations, which are frequently treated with tyrosine kinase inhibitors such as afatinib, dacomitinib, erlotinib, gefitinib, lazertinib combined with amivantamab, or osimertinib. Rare mutations like exon 20 insertions often require specialized evaluation, as they do not respond to standard treatments.
Frequently Asked Questions
Is EGFR-positive lung cancer always hereditary?
No. According to Sarah Goldberg, MD, the vast majority of EGFR-positive lung cancers are not hereditary and result from spontaneous mutations occurring within lung cells over a lifetime.
What is the significance of the T790M mutation?
The T790M mutation is a rare variant that can appear as a germline mutation linked to non-smoking lung cancer risk or emerge in somatic cells as a driver of resistance to targeted anticancer therapies.
How doctors test for EGFR gene changes?
Doctors perform biomarker testing using a tissue biopsy from a tumor or a liquid biopsy utilizing blood or other body fluids to detect specific gene mutations.
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