Smoking has been shown to have drastic consequences for lifespan and disease progression, yet it is not a kiss of death. Almost half of lung cancer patients have never smoked and only around 10 percent of smokers will get lung cancer. When it comes to acceleration of the aging process, however, the case has seemed more clear, and that certainly impacts the risk of death and disease, because age is the biggest risk factor for almost everything.
Yet a new study shows even that is not clear-cut. Using long-lived smokers as their phenotype, the authors of a study published in The Journals of Gerontology, Series A: Biological Sciences&Medical Sciences identified a network of single-nucleotide polymorphisms (SNPs - a DNA sequence variation occurring commonly within a population) that allow people to better withstand environmental damage (like smoking) and mitigate damage.
Collectively, these SNPs were strongly associated with high survival rates.
The findings suggest that longevity may be under the regulation of complex genetic networks which influence stress resistance and genomic stability, rather than being entirely determined by environmental factors. Genomic instability also happens to be one of the hallmarks of cancer pathogenesis, and so the same genes that may promote survival among smokers may also be important for cancer prevention. This is consistent with the findings of the study, which showed that the genes identified were associated with a nearly 11% lower cancer prevalence.
If so, there is reason to believe that long-lived smokers represent a biologically distinct group, endowed with genetic variants allowing them to respond differentially to environmental stressors.
Morgan E. Levine, corresponding author of the study, said, “We identified a set of genetic markers that together seem to promote longevity. What's more, many of these markers are in pathways that were discovered to be important for aging and lifespan in animal models. There is evidence that these genes may facilitate lifespan extension by increasing cellular maintenance and repair. Therefore, even though some individuals are exposed to high levels of biological stressors, like those found in cigarette smoke, their bodies may be better set up to cope with and repair the damage.”