(RxWiki News) The number of people in the US who smoke is on the decline, and those who do smoke may be doing so for shorter periods of time. Changed smoking patterns, however, may be causing some patients at risk for lung cancer to miss out on cancer screening.
A new study found that fewer people in recent years met the criteria for lung cancer screening — even some who might have gone on to develop lung cancer.
"Our findings may reflect a [change over time] in smoking patterns in which the proportion of adults with a 30 pack-years smoking history and having quit within 15 years declined," wrote Yi Wang, MD, of the Mayo Clinic in Rochester, MN, and colleagues.
The term "pack years" refers to how many years a patient smokes one pack a day. In this case, 30 pack years refers to patients who smoked one pack a day for 30 years — or the equivalent. An equivalent would be a patient who smoked two packs a day for 15 years.
The US Preventive Services Task Force (USPSTF) recommends a computed tomography (CT) scan for people at high risk for lung cancer — heavy smokers who are still smoking or have quit. This scan can identify lung cancer in patients, but it also uses radiation, which is thought to raise patients' risk of cancer if they are exposed too much.
These researchers reviewed data from more than 1,300 patients who were diagnosed with lung cancer from 1984 to 2011. They looked to see if the patients' medical history would have made them candidates for the USPSTF lung cancer screening.
The USPSTF guidelines recommended that people ages 55 to 80 who smoked 30 pack years should be screened for lung cancer with a CT scan. This included people who were still smoking and those who had quit within the last 15 years.
Dr. Wang and team found that the proportion of smokers who had smoked for 30 years declined and the proportion of smokers who quit more than 15 years ago increased.
Changes in those factors meant that fewer people met the criteria for high-risk lung cancer screening by CT.
From 1984 to 1990, 56.8 percent of the patients in this study would have met the screening criteria, but from 2005 to 2011, only 43.3 percent of the patients would have been screened.
"The decline in the proportion of patients meeting the USPSTF high-risk criteria indicates than an increasing number of patients with lung cancer would not have been candidates for screening," Dr. Wang and team wrote. "More sensitive screening criteria may need to be identified while balancing the potential harm from computed tomography."
This study was published online Feb. 24 in JAMA.
Grants from the National Institutes of Health and the National Institute on Aging, as well as funding from the Mayo Clinic Foundation, funded this research. Dr. Wang and team disclosed no conflicts of interest.