From the Journals

RCT confirms CT scan screening catches lung cancer early



CT scan screening of older people with heavy smoking histories – using lesion volume, not diameter, as a trigger for further work-up – reduced lung cancer deaths by about 30% in a randomized trial from the Netherlands and Belgium with almost 16,000 current and former smokers, investigators reported in the New England Journal of Medicine.

The Dutch-Belgian lung-cancer screening trial (Nederlands-Leuvens Longkanker Screenings Onderzoek [NELSON]) is “arguably the only adequately powered trial other than the” National Lung Screening Trial (NLST) in the United States to assess the role of CT scan screening among smokers, wrote University of London cancer epidemiologist Stephen Duffy, MSc, and University of Liverpool molecular oncology professor John Field, PhD, in an accompanying editorial.

NLST, which used lesion diameter, found an approximately 20% lower lung cancer mortality than screening with chest x-rays among 53,454 heavy smokers after a median follow-up of 6.5 years. The trial ultimately led the U.S. Preventive Services Task Force to recommend annual screening for people aged 55-80 years with a history of at least 30 pack-years.

European countries have considered similar programs but have hesitated “partly due to doubts fostered by the early publication of inconclusive results of a number of smaller trials in Europe. These doubts should be laid to rest,” Mr. Duffy and Dr. Field wrote.

“With the NELSON results, the efficacy of low-dose CT screening for lung cancer is confirmed. Our job is no longer to assess whether low-dose CT screening for lung cancer works; it does. Our job is to identify the target population in which it will be acceptable and cost effective,” they added.

The 15,789 NELSON participants (84% men, with a median age of 58 years and 38 pack-year history) were randomized about 1:1 to either low-dose CT scan screening at baseline and 1, 3, and 5.5 years, or to no screening.

At 10 years follow-up, there were 5.58 lung cancer cases and 2.5 deaths per 1,000 person-years in the screened group versus 4.91 cases and 3.3 deaths per 1,000 person-years among controls. Lung-cancer mortality was 24% lower among screened subjects overall, and 33% lower among screened women. The team estimated that screening prevented about 60 lung cancer deaths.

Using volume instead of diameter “resulted in low[er] referral rates” – 2.1% with a positive predictive value of 43.5% versus 24% with a positive predictive value of 3.8% in NLST – for additional work-up, explained investigators led by H.J. de Koning, MD, PhD, of the department of public health at Erasmus University Medical Center in Rotterdam, the Netherlands.

The upper limit of overdiagnosis risk – a major concern with any screening program – was 18.5% with NLST versus 8.9% with NELSON, they wrote.

In short: “Volume CT screening enabled a significant reduction of harms (e.g., false positive tests and unnecessary work-up procedures) without jeopardizing favorable outcomes,” the investigators wrote. Indeed, an ad hoc analysis suggested “more-favorable effects on lung-cancer mortality than in the NLST, despite lower referral rates for suspicious lesions” and the fact that NLST used annual screening.

“Recently,” Mr. Duffy and Dr. Field explained in their editorial, “the NELSON investigators evaluated both diameter and volume measurement to estimate lung-nodule size as an imaging biomarker for nodule management; this provided evidence that using mean or maximum axial diameter to assess nodule volume led to a substantial overestimation of nodule volume.” Direct measurement of volume “resulted in a substantial number of early-stage cancers identified at the time of diagnosis and avoided false positives from the overestimation incurred by management based on diameter.”

“The lung-nodule management system used in the NELSON trial has been advocated in the European position statement on lung-cancer screening. This will improve the acceptability of the intervention, because the rate of further investigation has been a major concern in lung cancer screening,” they wrote.

Baseline characteristics did not differ significantly between the screened and unscreened in NELSON, except for a slightly longer duration of smoking in the screened group.

The work was funded by the Netherlands Organization of Health Research and Development, among others. Mr. Duffy and Dr. de Koning didn’t report any disclosures. Dr. Field is an advisor for AstraZeneca, Epigenomics, and Nucleix, and has a research grant to his university from Janssen.

SOURCE: de Honing HJ et al. N Engl J Med. 2020 Jan 29. doi: 10.1056/NEJMoa1911793.

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