Low-dose CT for lung cancer: To screen or not to screen?
Duffy SW, Field JK. Mortality Reduction with Low-Dose CT Screening for Lung Cancer. N Engl J Med. 2020 Feb 6;382(6):572-573. doi: 10.1056/NEJMe1916361. Epub 2020 Jan 29. PubMed PMID: 31995680.
Screening high-risk patients for lung cancer with volume-based low-dose computed tomography (CT) reduces lung-cancer mortality.
This study involved 15,792 persons (13,195 men were originally planned; subsequently, a smaller number of women were invited). The study participants were from 50 to 74 years of age, either currently smoking or having quit ≤10 years earlier and having smoked daily >15 cigarettes for >25 years or >10 cigarettes for >30 years. Screening CT scans were to be performed at entry into the study and at 1, 3, and 5.5 years thereafter. The expected mortality rate without screening was 3.4 per 1000 person-years, based on mortality data derived from national databases in the Netherlands and Belgium.
At baseline, the median age of men was 58 years, with a median of 38 pack-years of smoking; 55.0% were current smokers. Of those invited to active screening, 90.0% underwent the expected procedures (22,600 CT scans in total) and 9.2% of those were followed by additional scans due to indeterminate results of the original procedures (19.7% of the first scans were indeterminate). There were 467 scans (2.1%) considered positive, which led to the detection of 203 cases of lung cancer (0.9% of all scans), with 1.2% of scans considered false-positive.
After 10 years of follow-up, the percentage of male participants with a diagnosis of lung cancer was higher among screened than unscreened men (5.58 cases per 1000 person-years vs 4.91 cases per 1000 person-years). Lung-cancer mortality was lower in the screening group compared with the control group, with 2.50 deaths per 1000 person-years versus 3.30 deaths per 1000 person-years, respectively. The rate ratio (RR) for lung cancer death was 0.76 (95% CI, 0.61-0.94).
Among the smaller number of female participants, the RR for lung cancer at 10 years was 0.67 (95% CI, 0.38-1.14).
The overall risk of death among male participants was unchanged (RR, 1.01; 95% CI, 0.92-1.11).
In the accompanying editorial the authors conclude that screening of >7900 persons (both men and women) with 4 rounds of CT scans reduces the number of people dying from lung cancer by ~60; this results in an estimated number of at-risk persons needed to screen of ~130 (with >500 scans) to avoid 1 death from lung cancer in the 10 year-program.