A rare inherited genetic mutation has been identified as a significant risk factor for lung cancer, particularly among nonsmokers, according to recent research. The mutation, known as T790M in the epidermal growth factor receptor (EGFR) gene, can increase the likelihood of developing lung cancer by as much as 62 times in individuals who have never smoked. Among smokers carrying the mutation, the risk rises to 25 times compared to those without it.

While tobacco use remains the leading cause of lung cancer, increasing risk by approximately four times in the general population, this new finding highlights that genetic factors can also play a critical role in the disease's development. Lung cancer is currently the second most common cancer in the United States and the leading cause of cancer-related deaths for both men and women, according to the American Cancer Society.

The EGFR gene encodes a protein that regulates cell growth and division. Mutations in this gene, including T790M, can cause uncontrolled cell proliferation, leading to cancer. Researchers analyzed genotyping data from 3.37 million individuals through the 23andMe platform to assess the prevalence and impact of the T790M mutation. The mutation was found in approximately one in 15,850 people.

Throughout the study, scientists evaluated the association between the T790M mutation and a broad range of 17 cancers and non-pulmonary conditions. However, a statistically significant link was observed only with lung cancer. The presence of EGFR mutations, including T790M, accounts for roughly 10 to 15 percent of lung cancer cases in the United States, with higher frequencies reported in Asian populations, as noted by the American Lung Association.

These findings underscore the importance of genetic testing and personalized risk assessment, particularly for nonsmokers who develop lung cancer without traditional risk factors. Further research may help improve early detection and targeted therapies for patients carrying this and other EGFR mutations.