A recent study published in the Journal of the National Cancer Institute by Washington University researchers found that smokers who have a determined genetic variation are significantly more predisposed to continue smoking longer in comparison to those who do not have that gene variant. These individuals are also more likely to receive a diagnosis of lung cancer at a younger age. The findings might result in efforts to change the way screening patients for lung cancer is performed.
This study assessed 24 different trials that enrolled over 29,000 smokers of European ancestry and determined that smokers with a variation in the CHRNA5 gene, a nicotine receptor gene, were more prone to keep smoking for 4 years longer than those without the genetic variant. The study also determined that these individuals are more likely to receive an earlier lung cancer diagnosis when compared to those who do not carry the genetic variation.
“People with the risk variant average a four-year delay in the age at which they quit smoking. Instead of quitting at age 52, which was the average age when study participants with a normal gene stopped smoking, people with the genetic variant quit at age 56,” said the study’s first author Dr. Li-Shiun Chen in a university press release.
The author explained that moreover those with the variant inhale smoke more deeply while smoking. The combination of genes and behaviour results in the development of lung cancer earlier in their lives. Dr. Chen continued in the press release, “They are likely to be diagnosed four years earlier. In those with lung cancer, the average smoker without the gene variant is diagnosed at age 65. Those with the greater genetic risk tend to be diagnosed at 61.”
The researcher explained that individuals who carry this gene variant should undergo screening at younger ages. Previous studies from Dr. Chen and her colleague Laura Jean Bierut demonstrated that those with the genetic variation are more likely to respond to medications to help them quit smoking, which is why knowing in advance about this predisposition may result in a more accurate, individualized therapy.
“The same people with this high-risk gene are more likely to respond to smoking-cessation medications, such as nicotine-replacement patches, lozenges or gum. Although it’s clear the gene increases the chances a person will develop lung cancer at a younger age, it also is clear that the risk can be reversed with treatment,” Dr. Chen said.
Lung cancer is related to very low survival rates and is the most frequent cancer worldwide. About 50 percent of all lung cancer patients die within a year after they receive the diagnosis; These numbers further highlight the necessity of screening patients as early as possible. This study supports the idea of using genetic information to choose alternative groups of people that would not be screened based solely on age or smoking history.
“Adding this information to screening criteria could help us focus our resources on people at the highest risk. In addition, knowing that they are the ones most likely to respond to nicotine-replacement therapy could allow us to respond with treatments that are more likely to be effective,” Dr. Bierut added.
