The international team of researchers has shown that the development of cancer in non-smoking people is explained by certain sets of mutations caused by natural processes in the body, and allocated three new subtypes of such diseases. The article of scientists was published in the magazine Nature Genetics.
On non-smoking people accounted for 10 to 25 percent of lung cancer. A group of specialists from the National Institute of Oncology of the United States together with colleagues from Canada and Europe sequenced the genome of tumors of 232 patients with non-cellular lung cancer, which previously never smoked. Of these, 189 had adenocarcin – the most common form of lung cancer, 36 – carcinoid tumor.
Scientists analyzed the presence of tumors of mutational signatures – mutation patterns, correlated with certain processes in the body (both natural and caused by carcinogenic substances). It turned out that most mutational signatures in the genomes of tumors of non-smoking people are associated with the internal processes of the body. The researchers also found mutational signatures associated with smoking – including 62 people who were exposed to surrounding tobacco smoke.
Analysis allowed researchers to distinguish three new lung cancer subtype in non-smokers ranging in terms of noise – the amount of changes in the genome in the tumor. The subtype of Piano (with the least amount of them) is associated with the activation of precursor cells and grows over the years, and Metzo-Forte is characterized by mutations in the EGFR gene and grows faster. With “Forte” there is a complete doubling of genome and other large shifts in the structure of the DNA of the tumor – which is most like a lung cancer in smokers.