Smokers who think they're healthy because they don't have symptoms of lung disease might just be fooling themselves. A small new study shows that lighting up leads to damage to airway cells, even if the smoker doesn't seem to have any health issues. And researchers noted that the changes to the airway cells had similarities to aggressive lung cancer.
"The study doesn't say these people have cancer, but that the cells are already starting to lose control and become disordered," study researcher Dr. Ronald G. Crystal, chairman and professor of genetic medicine at Weill Cornell Medical College, said in a statement. "The smoker thinks they are normal, and their doctor's exam is normal, but we know at the biologic level that all cigarette smokers' lungs are abnormal to some degree."
The study, published in the journal Stem Cell, involved 21 nonsmokers who were healthy, as well as 31 smokers who didn't have any symptoms of lung disease. All the study participants underwent X-rays and chest exams, as well as a procedure where the inside of their airways were "brushed" to collect airway epithelium cells. These cells are known to be where cancer originates, since they are directly affected by cigarette smoke.
Researchers found that there were changes to the human embryonic stem cell genes that came from the airway cells of the smokers, in that these genes had been turned "on." They noted that this bears similarity to aggressive cancer, where the particular genes are also "on."
The study authors pointed out that this turning "on" of the stem cell genes is important because healthy cells in the body are supposed to only be turned "on" to do what they are supposed to do. For instance, a lung cell gene whose expression is turned on means it is only supposed to contribute to a lung function. But the researchers found that "when you smoke a cigarette, some of the genetic programming of your lung cells is lost," Crystal said in the statement. "Your cells take on the appearance of a more primitive cell. It doesn't necessarily mean you will develop cancer, but that the soil is fertile to develop cancer."
And it's not just smokers who face the health risks of lighting up -- a recent study in the journal Mutagenesis showed that thirdhand smoke -- which is the residue that clings to surfaces after exposure to secondhand smoke -- can also spur DNA damage, and the harm can become worse with time.