Genetic analysis of people who do not have a history of smoking has been able to find out the origin of lung cancer among non-smokers. The study has been led by an international group of scientists from the National Cancer Institute (NCI) that is a part of the National Institutes of Health. For the first time, the genomic analysis has shown three molecular subtypes of lung cancer in people who have never smoked in their lives. The authors of the study have said that most of these tumors are an upshot of the accumulation of mutations that are caused by natural processes, which take place in the body. Health experts have claimed that the findings of the study will help solve the mystery of how lung cancer is diagnosed among people who have never smoked in their lives. The findings of the study will help experts in developing an effective and targeted treatment for the dreaded disease. The lead author of the study, Maria Teresa Landi has said that the team has seen some diverse subtypes of lung cancer among non-smokers. These subtypes have distinct molecular traits and evolutionary processes. Dr. Maria Teresa Landi is appointed as an epidemiologist of the Integrative Tumor Epidemiology division of the NCI’s Department of Cancer Epidemiology and Genetics. The study has been done in association with the National Institute of Environmental Health Sciences that is also a part of the NIH. The authors of the genomic analysis have said that with the new findings, they are sure they will be able to come up with different types of treatments that are based on these subtypes. The findings of the study have been reported in the journal called Nature Genetics.
Experts have said that lung cancer is one of the leading causes of death that are linked to cancer across the globe. As per the latest report, more than 2 million people are detected with the dreaded disease each year around the world. People who are diagnosed with lung cancer usually have a history of tobacco smoking; however, on the other hand, nearly 10 to 20 percent of people who are diagnosed with lung cancer have never smoked tobacco in their lives. The findings of the study have noted that lung cancer that takes place in nonsmokers usually occurs in women at an early age as compared to people who are smokers and suffering from lung cancer. The authors of the study have said that certain environmental factors such as exposure to passive tobacco smoking, asbestos, air pollution, radon, and having past lung issues contribute to the diagnosis of lung cancer among non-smokers. However, scientists have not been certain about what leads to most of such lung cancer incidents among people who do not smoke. In this large-scale analysis, scientists have done whole genome sequencing to exemplify the genetic changes in tumor tissues.
The authors of the study have matched normal tissue that has been extracted from 232 non-smoker people and most of these people have been European descendants who have been diagnosed with non-small cell lung cancer. Experts have said that their tumors have contained 189 adenocarcinomas, 36 carcinoids, and 7 other tumors of different types. Adenocarcinoma is one of the most common types of lung cancer, said the experts. The participants of the study have not been given any treatment before the genomic study. The authors of the study have tested the tumor genomes for mutational signatures that are blueprints of mutations, which are linked to particular mutational activities in the body. Experts have said that mutational markings or signatures are like archives of activities in the tumor that leads to the buildup of mutations. Mutational signatures offer traces into what has led to the development of cancer. There is a wide range of mutational signatures that exists; however, some signatures have no definite cause. In the study, experts have said that most of the tumor genomes of people who have never smoked undergo mutational markings that are linked to damage from endogenous activities, which take place in the body naturally.
The study has been focusing on people who have never smoked in their lives; therefore, experts have not been able to find any mutational markings that have been linked to direct exposure to tobacco smoking in the past. They have not been able to find mutational signatures among 62 people who have been exposed to passive tobacco smoking. The lead author of the analysis has said that the sample size of the study has been limited. Dr. Landi has said that there is a need for a larger sample size with detailed information to determine the actual impact of passive tobacco smoking on lung cancer in people who have been non-smokers all their lives. The study has found three new subtypes of lung cancer among non-smokers and these subtypes have been given mucosal names depending on the level of noise, which is defined as the number of genomic changes in the tumor. The piano subtype has been the dominant one that has few mutations. Experts have said that this subtype seems to be linked to the start of progenitor cells that are responsible for the generation of new cells. They have said that the piano subtype grows quite slowly over many years; this subtype is not easy to treat as it might have many diverse driver mutations.
The second subtype that has been named as the mezzo-forte subtype contains particular chromosomal changes and mutations as well in the growth factor receptor gene EGFR. The third forte subtype has shown whole-genome doubling; it is a genomic change, which is usually seen in smokers who are dealing with lung cancer. This subtype as well grows quite rapidly. The lead author has claimed that the team has tried to differentiate subtypes that might have diverse methods for prevention and care. Dr. Landi has said that the piano subtype as it grows slowly will give doctors enough time to detect such tumors at the earliest when they are not hard to treat. On the other hand, mezzo and forte subtypes do not have many driver mutations, which means such tumors can easily be diagnosed with a single biopsy and people who are dealing with such kinds of tumors might get some relief from targeted therapies. Now, experts are going to evaluate people who belong to different ethnic backgrounds and geographic locations in further studies. Dr. Maria Teresa Landi has said that experts have just started to understand the evolution of lung cancer in people who have not been indulged in tobacco smoking in their lives. There is clear diversity in lung cancers in never-smoking people, said the experts.