Declines in smoking rates may adversely affect early lung cancer detection and increase mortality rates as fewer patients qualify for low-dose CT screenings under current guidelines, according to a study published in the Feb. 24 edition of the Journal of the American Medical Association.
The current guidelines, set by the U.S. Preventative Services Task Force (USPSTF), recommend annual low-dose screenings for eligible patients, defined by USPSTF as “adults aged 55 to 80 years who have a 30 pack-year smoking history and currently smoke or have quit within the past 15 years.” The Centers for Medicare and Medicaid Services (CMS) recently approved coverage of annual lung CT scans for similarly defined high-risk beneficiaries.
But those parameters miss a substantial number of at-risk patients who don’t qualify for testing, according to Ping Yang, MD, PhD, an epidemiologist at Mayo Clinic Cancer Center in Rochester, Minn., who says recent anti-smoking trends have resulted in an increase in the number of heavy smokers who quit the habit earlier in life. “As smokers quit earlier and stay off cigarettes longer, fewer are eligible for CT screening, which has been proven effective in saving lives,” Yang said in a statement. “Patients who do eventually develop lung cancer are diagnosed at a later stage when treatment can no longer result in a cure.”
Yang and colleagues at the Rochester Mayo Clinic Cancer Center conducted a retrospective analysis of all residents above the age of 20 who lived in Olmsted County, Minn., from 1984 to 2011 using the Rochester Epidemiology Project database to determine cases of lung cancer among the sample of some 140,000 people. The analysis showed that among the 1,351 people who developed lung cancer during that time, the number of patients who smoked at least 30 pack-years declined, while the number of those who had quit for more than 15 years increased.
While the decline in smoking is a positive development, the results of the study show a troubling side effect, according to Ying, as the percentage of patients who would’ve qualified for CT screening fell steadily over the same timeframe, from 57 percent between 1984-1990 to 43 percent from 2005–2011. “While more people have quit for a longer period of time, they are still getting lung cancer and they make up a larger proportion of newly diagnosed lung cancer patients,” she said. “That means more patients are going to be diagnosed at a later stage, because they could not take advantage of early detection.”
New standards for lung cancer CT screening eligibility need to be developed by policymakers while also weighing the dangers of radiation exposure with the benefits of early cancer detection through medical imaging, says Ying. “There are ways to screen at-risk patients while still avoiding false alarms and overtreatment,” she adds. “Researchers need to discover biological markers, such as genetic or physiological traits, to help them better identify high-risk patients.”