New evidence suggests that people who quit smoking may be able to undo some amount of lung damage that smoking causes. Reseachers have discovered that Clara cell 10 kDa (CC10), a protein which is found in the alveolar fluid lining the lungs, significantly increases when a person quits smoking. While the biology of CC10 isn't completely understood, it is thought to be protective, shielding the respiratory tract from damage.
Smokers have less of this protein in their bloodstream than their non smoking counterparts, but it appears that some of this deficit may be reversed with smoking cessation.
Jiping Chen, M.D., Ph.D., a Cancer Prevention Fellow at the National Cancer Institute in Bethesda, MD, is the lead author of the study The Association Between the Anti-Inflammatory Protein CC10 and Smoking Status Among Participants in a Chemoprevention Trial.
In an effort to understand how CC10 levels are affected by smoking cessation, scientists measured CC10 in the bloodstream of 81 current smokers and 23 former smokers, with former smokers averaging approximately seven years of smoke free time. Also measured were samples from lung fluid in a procedure known as bronchoalveolar lavage. Of important note is the fact that all participants suffered from bronchial dysplasia, a precancerous lesion that put them at high risk for developing lung cancer.
With adjustments made for age, researchers found that former smokers had as much as 1.7 times the amount of CC10 in their bloodstream as current smokers. CC10 levels were higher in the lung fluid samples as well, though not significantly so.
According to Chen, this information looks hopeful: "This is good news for former smokers. It provides more evidence that quitting smoking can undo some of the damage to the lung resulting from tobacco exposure."
Source: The American Association for Cancer Research