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Low-dose computed tomography (LDCT) for lung cancer screening was associated with a reduction in lung cancer mortality, according to a meta-analysis of nine international randomized controlled trials.

When the latest U.K. Lung Cancer Screening Trial results were added to the meta-analysis, LDCT screening was associated with a 16% relative reduction in mortality compared with no LDCT (relative rate [RR] 0.84, 95% CI 0.76-0.92), reported John Field, PhD, of the University of Liverpool in England, during the virtual World Conference on Lung Cancer.

Previous studies, such as the National Lung Screening Trial and the NELSON trial, have provided evidence of a statistically significant reduction in lung cancer mortality with LDCT screening, with reductions of 20% and 24%, respectively.

The randomized controlled U.K. Lung Cancer Screening Trial compared LDCT screening with usual care in a high-risk population. This trial was not powered to find a lung cancer survival benefit, Field noted, and while the trial showed a trend toward a survival benefit, it could not be considered significant.

This trial "indicates a reduction of lung cancer death with similar magnitude to NELSON and the National Lung Screening Trial," Field said. "Its results were included in a meta-analysis of nine randomized trials, which provides unequivocal support for lung cancer screening in identified risk groups."

For the U.K. study, risks were calculated using the Liverpool Lung Project model, which incorporates age; smoking duration; family history of lung cancer; history of previous malignancies; exposure to asbestos; and other respiratory risk factors such as bronchitis, emphysema, tuberculosis, chronic obstructive pulmonary disease, and pneumonia. Cigar and pipe smoking are counted as conferring an identical risk to cigarette smoking.

Field and colleagues enrolled 4,055 participants from October 2011 to February 2013, with either a single invitation to LDCT screening or usual care. Data were collected on lung cancer cases and deaths to Feb. 29, 2020 through linkage to national registries. The primary outcome was mortality due to lung cancer.

After a median follow-up of 7.3 years, 30 of 1,987 patients in the LDCT group died from lung cancer compared with 46 of 1,981 patients in the usual care group (RR 0.65, 95% CI 0.41-1.02, P=0.062). Of note, the relative benefit in terms of lung cancer mortality was seen most strongly in the 3 to 6 years after randomization, said Field.

In this study, 61% of the cancers found were diagnosed at stage I, and possibly curative surgery could be performed for 83% of the cancers found, he noted.

Commenting on the study, Paul Wheatley-Price, MBChB, BSc, MD, of the University of Ottawa in Canada, suggested that the findings from this study are in line with what we already know about lung cancer screening. "We don't need any more trials," he said. "This question has been answered: low-dose CT scan screening is effective."

"As lung cancer incidence is so high, and diagnosis so common at late stages, low-dose CT is the single most important intervention to save lives," he added.

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