Researchers at the National Cancer Institute or NCI may have decoded the reason why many non-smokers are falling sick with lung cancer. Their research has shown that in people with no smoking history, the cancerous cells grow and multiply from the accumulation of mutations caused by natural processes in the body. The research was conducted by an international team, which is a part of the National Institutes of Health.
According to researchers, these findings are very important as they hold the answer to important and troubling questions as to why lung cancer affects people, who have no smoking history. This research is thought to be the foundation for more clinical treatment of non-smoking patients contracting cancer.
Commenting on the findings, Maria Teresa Landi of the Integrative Tumor Epidemiology Branch in NCI's Division of Cancer Epidemiology and Genetics, who led the study, said, "What we're seeing is that there are different subtypes of lung cancer in never smokers that have distinct molecular characteristics and evolutionary processes. In the future we may be able to have different treatments based on these subtypes."
In this extensive epidemiologic study, researchers made use of whole-genome sequencing to track the genomic changes in tumor tissue and matched normal tissue from 232 non-smokers, mostly of European descent, who were all diagnosed with non-small cell lung cancer. None of the patients had begun cancer treatment.
Researchers studied the tumor genomes for mutational signatures, which are patterns of mutations related to specific mutational processes, like damage from natural activities in the body or any exposure to carcinogens. These mutational signatures are the tumor's record of activities that led up to the accumulation of mutations. These mutational signatures provide vital information as to why cancer develop. In the case of non-smokers, the study found that most of the tumor genomes had mutational signatures related to damage from endogenous processes, which is also known as the natural processes taking place in the human body.
Globally, lung cancer is one of the main causes of cancer deaths. While most people who contract lung cancer smoke, while around 10%-20% cancer patients are non-smokers. And even among them, women fall sick with lung cancer more than men.
Outside factors like second-hand tobacco smoke, radon, air pollution, and asbestos, can be considered as some of the reasons for non-smokers contracting the diseases, but there has never been proper medical research to back up these claims.
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