The decline in smoking rates will translate to fewer people qualifying for lung cancer screening with low-dose CT, thereby potentially leading to higher rates of lung cancer mortality, according to researchers at Mayo Clinic.
The U.S. Preventive Services Task Force issued a recommendation in December 2013 that annual lung cancer screening with low-dose CT be offered to adults aged 55 to 80 years who have a 30 pack-year smoking history and either still smoke or quit within the past 15 years. In February, CMS agreed to cover screening for Medicare beneficiaries aged 55 to 77 years who meet the same smoking criteria outlined in the USPSTF recommendation.
However, the percentage of American adults who smoke declined from 20.9% in 2005 to 17.8% in 2013, according to CDC.
“As smokers quit earlier and stay off cigarettes longer, fewer are eligible for CT screening, which has been proven effective in saving lives,” Ping Yang, MD, PhD, an epidemiologist at Mayo Clinic Cancer Center in Rochester, Minnesota, said in a press release. “Patients who do eventually develop lung cancer are diagnosed at a later stage when treatment can no longer result in a cure.”
In a retrospective study, Yang and colleagues evaluated data on about 140,000 people aged older than 20 years who lived in Olmstead County, Minnesota. They identified 1,351 individuals who developed incident primary lung cancer between 1984 and 2011.
Among that group, those who had a minimum 30 pack-year history of smoking declined during the study period, whereas the proportion of those diagnosed with lung cancer who had quit smoking more than 15 years prior increased during the study period.
This translated to a steady decline of patients with lung cancer who would have been eligible for lung cancer screening under current criteria.
From 1984 to 1990, 56.8% (95% CI, 50.8-62.9) of those in the study cohort diagnosed with lung cancer would have been eligible for low-dose CT scans. From 2005 to 2011, 43.3% (95% CI, 38.4-48.2) would have been eligible for screening.
The proportion of men who would have met smoking history criteria for screening declined from 60% to 50% during the study period, and the proportion of women who would have met smoking history criteria declined from 52.3% to 36.6%.
Policymakers and researchers must collaborate to change screening criteria to ensure a higher percentage of lung cancer cases are detected in early stages, Yang and colleagues concluded.
“The existing screening program will become less effective at reducing lung cancer mortality in the general population if they continue to use the same criteria,” Yang said. “We don’t want to penalize people who succeeded in smoking cessation.”
However, the researchers acknowledged there are potential dangers associated with relaxing lung cancer screening criteria too much. Those risks include higher costs, unnecessary radiation exposure and higher rates of false-positive results, which could lead to overtreatment.
“There are ways to screen at-risk patients while still avoiding false alarms,” Yang said in the release. “Researchers need to discover biological markers, such as genetic or physiological traits, to help them better identify high-risk patients.” – by Anthony SanFilippo
Disclosure: The researchers report no relevant financial disclosures.