It Works—Study Shows Low-Dose CT Screening Reduces Lung Cancer-Specific Death Rate

November 12, 2020
Whitney J. Palmer
Whitney J. Palmer

Even potential for over-diagnosis does not appear to increase other causes of mortality.

Lung cancer screening with low-dose CT (LDCT) has been relatively slow to catch on in the United States, but a new analysis confirms that using the scans with high-risk individuals can reduce mortality.

In fact, according to a study published Nov. 11 in the Annals of Family Medicine, using LDCT can prevent one death for every 250 at-risk adults who are screened – a drop in lung-cancer specific mortality of 0.4 percent. These results, produced by a team of investigators from the University of Georgia, confirms the benefit of these screenings even in the face of potential over-diagnosis.

“[Our] meta-analysis…clearly demonstrates a reduction in lung cancer-specific mortality that is statistically, as well as clinically, significant,” said the team led by Mark H. Ebell, M.D., epidemiology and biostatistics professor.

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These findings are important, they said, because a Centers for Disease Control & Prevention study revealed that only 4.5 percent of eligible patients are currently undergoing lung cancer screening. And, many people are still being screened with chest X-ray.

To get a better idea of the reduced-mortality benefit LDCT can provide, Ebell’s team conducted a retrospective meta-analysis from Jan. 1, 2019, to Feb. 26, 2020, on eight studies that included health outcomes from 90,275 patients, comparing individuals who were screened with LDCT against those who received usual medical care or chest X-rays. The studies include patients who were current smokers with 20-to-30 pack-year histories, as well as those who gave up smoking within the past 10-to-15 years.

As part of their analysis, the team determined there was a significant reduction in the risk of death with LDCT screening compared to the control group – a relative risk of 0.81, they said. By applying that relative risk rate to the lung cancer-specific morality rate, they determined the 0.4 percent absolute risk reduction. That corresponded, they said, within 5.2-to-10 years of follow-up, to preventing one death per 250 high-risk patients screened. For all-cause mortality, they determined the absolute risk reduction was 0.34 percent, corresponding to the prevention of one death from any cause per 294 individuals.

“Although the absolute reduction in all-cause mortality was not statistically significant, it was of a similar magnitude as the reduction in lung cancer-specific mortality (0.34 percent versus 0.4 percent),” they said. “This similar is reassuring. Given the occurrence of over-diagnosis one cannot conclusively rule out substantial unintended harms of LDCT screening, but if present, they do not appear to increase other causes of mortality.”

Ultimately, the team said, their results fall in line with the U.S. Preventive Services Task Force recommendations for implementing CT-based lung cancer screenings in adults between age 55 and 80 who have a history of smoking. Consequently, there should be a greater push toward using these scans, they said.

“Measures to increase uptake of lung cancer screening and ensure adherence to follow-up protocols based on the best available evidence are needed,” they concluded.