A new study says lung cancer developed in smokers is quite different from that among non-smokers. There could be many DNA changes in tumors of those who haven’t had a puff before.

"We think this finding provides evidence that never-smoker and smoker lung cancers are different, and suggests they arise through different molecular pathways," study author Kelsie Thu said. "Never-smokers might be exposed to a carcinogen, not from cigarettes that causes their tumors to have more DNA alterations and promotes lung cancer development."

Keeping earlier studies as base, researchers now looked further and found more DNA alterations. They collected lung tumors and noncancerous tissue from 30 never-smokers, 39 current smokers and 14 former smokers.

They noted that people who never smoked earlier had more mutations in the genes that encode molecules called epidermal growth factor receptors (EGFRs), which receive signals on cell membranes, than current or former smokers. Researchers also found more alterations in the genomes of non-smokers. They also noted that most of the non-smokers were female.

But "EGFR mutations are not the only mutations driving cancer development in never smokers," Thu said, which is why she and her colleagues looked at all genes in the tumors they analyzed, to see broad regions of DNA that were different between smokers and non-smokers. Thu added that more research needs to be undertaken to validate the same.