Lung Screening May Encourage Smoking Cessation CME

News Author: Damian McNamara

CME Author: Charles P. Vega, MD, FAAFP Faculty and Disclosures

CME Released: 11/08/2012; Valid for credit through 11/08/2013

CLINICAL CONTEXT
There are more than 200,000 new cases of lung cancer diagnosed annually in the United States. However, effective screening strategies for lung cancer have remained elusive. Two major studies have recently evaluated the efficacy of lung cancer screening programs, and Barry and colleagues provide a review of this research. The Prostate, Lung, Colorectal and Ovarian Cancer (PLCO) trial did not find a difference in the rate of lung cancer mortality in comparing a screening group receiving annual chest X-rays with a control group. However, the National Lung Screening Trial demonstrated that individuals receiving lung cancer screening with computed tomography experienced a 20% reduction in the risk for mortality compared with adults screened with chest X-ray alone.

Smoking is the most important risk factor for lung cancer, and previous research suggests that false-positive screening tests for lung cancer are associated with a higher rate of cessation from smoking. The authors of the current study examined variables associated with smoking outcomes in the PLCO study.

STUDY SYNOPSIS AND PERSPECTIVE
Former smokers are more likely to relapse if they are young; black or Hispanic; less educated; unmarried; have a lower income, lower body mass index, and no family history of lung cancer; or have smoked light or ultralight cigarettes, according to a secondary analysis of participants in the PLCO Screening Trial.

Of the 31,694 self-reported former smokers at baseline in the PLCO, 3.3% relapsed and reported on follow-up that they currently smoked, report Samantha A. Barry, BA, from the Prostate Cancer Decision Making and Quality of Life Research Department at Georgetown University Medical Center, Washington, DC, and colleagues in an article published online October 26 in the Journal of the National Cancer Institute.

In addition, long-term smokers and recent quitters were statistically significantly more likely to relapse (both P < .001), according to this secondary analysis of PLCO trial data.

"This relapse prediction model may be useful for identifying former smokers who may benefit most from relapse prevention interventions," the authors note.

Of the 6807 people who reported smoking at baseline, 65.2% said they still smoked on their subsequent questionnaire a median of 8.5 years later (range, 4 - 14 years). Those who were younger, black or Hispanic, or had a lower income or a lower body mass index were more likely to have continued smoking.

"Continued smoking was also more likely among heavier smokers, smokers of light or ultralight cigarettes, and those with greater secondhand smoke exposure," the authors write. "However, current smokers with higher body mass index or new tobacco-related diseases and smokers of unfiltered cigarettes were less likely to continue smoking. These characteristics may be useful in identifying smokers who are most in need of a smoking cessation intervention."

In terms of trial variables, only participation in the PLCO trial for a shorter time was associated with continuation of smoking (odds ratio, 0.85; 95% confidence interval, 0.82 - 0.88). The trial group randomization (screening vs control), screening center, and screening result were not significant factors.

Participants were approximately 60 years old, 50% were men, 90% were white, and about 50% had 2 or more comorbidities. They started smoking at an average age of 18 or 19 years. In addition, 10% reported receiving at least a single false-positive screening result, defined as a positive chest X-ray at 1 or more of the 4 annual assessments that was not followed by a lung cancer diagnosis within 3 years.

Receipt of a false-positive screen was not significantly associated with lower likelihood of smoking relapse or greater likelihood of smoking cessation, however, "suggesting that screening results may have only a short-term effect on smoking behavior," the authors note. "However, we found that being diagnosed with a new noncancer, tobacco-related disease was inversely associated with continued smoking, suggesting another possible teachable moment for altering smoking behaviors: Upon receiving a new diagnosis, smokers may be motivated to quit smoking and become more amenable to formal cessation programs."