Why Some Smokers Never Get Cancer

A new study published in the journal Nature offers clues as to why some lifelong smokers never develop cancer, while some non-smokers do. The research indicates that a person’s genetic makeup can play a major role in determining how cancer evolves after DNA damage occurs. Scientists discovered that inherited genetic variations, even relatively small ones, can influence how tumours evolve following exposure to the same carcinogen, affecting which mutations develop, how the tumour forms, and potentially how it responds to treatment. In the study, researchers used four genetically distinct strains of mice to mirror the genetic diversity found in humans. All mice were given the same controlled dose of the carcinogen diethylnitrosamine (DEN), a compound found in tobacco smoke and some processed foods, at the same age. Despite identical exposure, the cancer developed through different evolutionary pathways depending on the genetic background of each strain. Analysis of nearly 600 tumours revealed that while many ultimately activated the same biological processes driving growth, they reached that state through different genetic mutations and changes. The findings demonstrate that cancer is not solely influenced by external carcinogen exposure but is also significantly shaped by an individual’s inherent genetic makeup.