A recent study indicated that current screening criteria for lung cancer in smokers should be revised to include those who quit smoking more than 15 years ago. The study, “Trends in Subpopulations at High Risk for Lung Cancer,” was published in the Journal of Thoracic Oncology.
Lung cancer is linked to an abnormal cell growth in lung tissue and one of the main causes for the disease is smoking.
“A decline in smoking rates has been, and continues to be, a critical step to reduce lung disease risk and deaths,” said the study’s lead author, Dr. Ping Yang, an epidemiologist at Mayo Clinic Cancer Center, in a news release.
Symptoms of lung cancer often emerge once the disease is already at an advanced stage. But the current lung disease screening criteria set by the U.S. Preventive Services Task Force (USPSTF) is restricted to people ages 55-80 who have smoked a minimum of one pack per day for 30 years and are either still smoking, or have quit within 15 years.
A previous study by Dr. Yang and coworkers revealed that two-thirds of U.S. patients diagnosed with lung cancer actually did not qualify for screening under the current USPSTF criteria, suggesting that not all individuals who are at risk of lung cancer are qualified to benefit from early detection using low-dose computed tomography (CT) scans. As a result, the researchers suggest that current screening criteria should be revised to include those at high risk.
To determine the individuals at high risk of developing lung cancer, the researchers examined two groups of lung cancer patients: a hospital cohort of up to 5,988 individuals referred to Mayo Clinic, and a community cohort of about 850 residents in Olmsted County, Minnesota.
The results suggested that the highest percentage of lung cancer patients who did not meet the current USPSTF screening criteria corresponded to those who quit smoking for 15 to 30 years — 12 percent of the patients from the hospital cohort group and 17 percent of those from the community cohort group.
“We were surprised to find that the incidence of lung cancer was proportionally higher in this subgroup compared to other subgroups of former cigarette smokers,” Yang said. “The common assumption is that after a person has quit for so many years, the lung cancer rate would be so low that it wouldn’t be noticeable. We found that assumption to be wrong. This suggests we need to pay attention to people who quit smoking more than 15 years ago, because they are still at high risk for developing lung cancer.”
The research team suggested that more large-scale studies should be conducted in populations outside Olmsted County, and if the results are corroborated, USPSTF screening criteria should be revised to include individuals who quit smoking more than 15 years ago.
“Lung cancer rates are dropping because smoking is decreasing, but that doesn’t mean that our current screening parameters are good enough,” Yang said. “It is understandable, because the relative importance of risk factors changes over time. We need to adjust screening criteria periodically, so we can catch more lung cancers in a timely fashion. Based on our data, which are more recent and come from a well-defined population, I think we should take action to screen this group, which is at high risk of developing the disease.”