Data from an analysis of lung cancer screening programs in Italy add further evidence that smoking cessation reduces mortality. Heavy smokers screened by low-dose computed tomography (CT) who stopped smoking before or during the screening period had a three- to fivefold reduction in mortality compared with current smokers. The data were presented at the 16th World Conference on Lung Cancer.1
“Stopping smoking is associated with a significant reduction of the overall mortality of heavy smokers enrolled in [low-dose CT] screening programs. The benefit of stopping smoking appears to be three- to fivefold greater than the one achieved by earlier detection in the National Lung Screening Trial (NLST),” said lead researcher Ugo Pastorino, MD, Director Thoracic Surgery, IRCCS Istituto Nazionale dei Tumori Foundation, Milan, Italy. The NLST had previously found a 7% reduction in all-cause mortality with low-dose CT screening, he indicated.
In the current study, the Italian investigators analyzed 3,381 heavy smokers enrolled in two low-dose CT screening programs. They divided patients according to whether they were current smokers (also including those who quit smoking less than 1 year before the end of follow-up or death) or former smokers; former smokers could be ex-smokers at the time of baseline screening or smokers who stopped smoking during the screening period, at least a year before the end of follow-up or death (ie, quitters).
The population included 1,801 current smokers, 872 ex-smokers, and 708 quitters. The percentage of baseline smokers who quit during the low-dose CT screening period was 28%.
After almost 9 years of follow-up, there were 151 deaths among the smoking group and 109 deaths among enrollees who stopped smoking during the screening period (50 among ex-smokers and 59 among quitters). The all-cause mortality for current smokers was 846 per 100,000 pack-years and for former smokers was 726 per 100,000 pack-years. Multivariate analysis, adjusted for age, gender, lung function, and pack/years, revealed a relative risk of death of 0.75 to 0.57 for ex-smokers and quitters. This finding amounted to a relative risk reduction of 26% for former smokers vs current smokers and 43% for quitters vs current smokers, Dr. Pastorino said.
“The difference between the mortality curves was consistent throughout the period of observation. The two curves diverged nicely,” he added.
Lung cancer deaths accounted for about one-third of all deaths and numbered 45 of 17,846 person-years among current smokers, 11 of 7,809 person-years among ex-smokers, and 17 of 7,202 person-years among quitters.
The analysis also identified other risk factors for mortality. These risk factors and their associated risk ratios included male sex (1.6); age older than 62 years (3.2); forced expiratory volume, first second (FEV1) < 80% (2.5); packs/year ≥ 40 (1.5); and total cigarettes ≥ 292,200 (1.5).
Investigators also evaluated the benefit of pharmaceutical support in a smoking cessation program that involved a sample of 187 persons screened over 5 years. In this government-funded pilot observational study, the drug varenicline (Chantrix) plus behavioral intervention resulted in a quitting rate of 49% after 3 months, which declined but remained at 20% at 12 months, he reported.
“This tells us that pharmaceutical support is effective as part of an intervention and that quitting is difficult, but if you do it systematically, with repeated interventions, you can achieve more,” commented Dr. Pastorino. “You have to do it more than once if you want to maintain the effect.”
“The take-home message is that stopping smoking is the most effective and feasible strategy to reduce mortality in current smokers,” Dr. Pastorino said. He added that the next step along this path is to combine preventive efforts with screening to further reduce mortality among smokers. ■
Disclosure: Dr. Pastorino reported no potential conflicts of interest.
1. Pastorino U, Boffi R, Marchiano A, et al: Stopping smoking reduces mortality in low-dose computed tomography screening volunteers. 16th World Conference on Lung Cancer. Abstract PLEN04.07. Presented September 9, 2015.