CT screening cuts lung cancer mortality, greater benefit in women
Population-based lung cancer screening with multislice CT substantially reduces mortality from the disease among high-risk former and current smokers, with larger risk reductions in women vs men, the NELSON study has shown.
The results, presented at the International Association for the Study of Lung Cancer (IASLC) 19th World Conference on Lung Cancer (WCLC 2018), showed a 26 percent risk reduction in lung cancer mortality in men (95 percent confidence interval [CI], 0.60 to 0.91; p=0.003) and a 39 percent risk reduction in women (95 percent CI, 0.35 to 1.04; p=0.0543) who underwent screening compared with controls after 10 years of follow-up. [Koning H, et al, WCLC 2018, abstract PL02.05]
At 8-year and 9-year follow-up, men who underwent screening had a 25 percent (95 percent CI, 0.59 to 0.95; p=0.015) and 24 percent (95 percent CI, 0.60 to 0.95; p=0.012) reduction in risk of lung cancer mortality, respectively.
“Strikingly, women who underwent screening had a 61 percent [95 percent CI, 0.18 to 0.78; p=0.0037] reduction in risk of lung cancer mortality at 8 years, and a 53 percent [95 percent CI, 0.25 to 0.84; p=0.0069] risk reduction at 9 years,” reported principal investigator Professor Harry de Koning of the University Medical Center Rotterdam, the Netherlands.
The study included 15,792 individuals aged 50–74 years who were smokers (>10 cigarettes/day for >30 years or >15 cigarettes/day for >25 years) or who had quitted smoking in the last ≤10 years. Participants were recruited from population-based registries in Belgium and the Netherlands. Those randomized to receive lung cancer screening (n=7,900) underwent CT scans at year 1 (n=7,557; 95.6 percent), year 2 (n=7,295; 92.3 percent), year 4 (n=6,922; 87.6 percent) and year 6.5 (n=5,279; 66.8 percent), while those in the control arm (n=7,892) received no screening.
“More than 80 percent of participants in each arm were men. About 55 percent were current smokers, and the median tobacco exposure was almost 40 pack-years,” said de Koning.
The overall screening uptake rate was 85.6 percent. A positive result was reported in 2.2 percent of the participants, while 9.3 percent had an indeterminate result and underwent further CT scans 3–4 months after the initial scans.
“The lung cancer detection rate was 0.9 percent, with a positive predictive value for a positive test result of 41 percent,” said de Koning. “In the screening arm, lung cancer cases were mainly in stage I, with just over 10 percent of the cases being in stage IV. In contrast, about half of the cases in the control arm were in stage IV.”
“Among male participants, there were 214 lung cancer deaths in the control arm and 157 lung cancer deaths in the screening arm. A clear difference was observed as early as in years 2–3,” he noted.
“The NELSON trial showed larger risk reductions in lung cancer mortality than the earlier NLST trial [National Lung Screening Trial],” said discussant Professor John Field of the University of Liverpool, UK. [Cancer 2013;119:3976-3983] “Based on the results of these two large, randomized controlled trials, there is now conclusive evidence for implementation of lung cancer screening, at least in Europe.”