LDCT Lung Cancer Screening: More Data for CMS

In a healthy population of patients aged 65 or older, low-dose computed tomography (LDCT) screening for lung cancer appears to provide a generally similar benefit to harm tradeoff as it does for younger patients, according to the results of a sub-analysis of data from the National Lung Screening Trial (NLST) published in Annals of Internal Medicine.

“The benefits and harms of LDCT screening in NLST were roughly similar by age group (under 65 vs. 65+),” study author Paul F. Pinsky, PhD, of the National Cancer Institute, told Diagnostic Imaging. “The findings should help inform [The Center for Medicare and Medicaid Services] in making their LDCT coverage decision.”

The Center for Medicare and Medicaid Services (CMS) is currently evaluating whether to offer coverage of LDCT screening for lung cancer to Medicare recipients. In April, Medicare Evidence Development and Coverage Advisory Committee (MEDCAC) panel voted low confidence that there was enough evidence to conclude that the benefits of LDCT screening outweighed its harms in the Medicare-aged population.

According to Pinsky, this low level of confidence was based, in part, on the fact that the NLST, the main body of evidence used by the United States Preventive Services Task Force (USPSTF) in making its recommendation for LDCT screening, was comprised primarily of patients younger than age 65, with only 25% of NLST patients 65 or older at entry. Therefore, it was not clear whether the overall favorable results of NLST also held in the 65+ population.

In this study, Pinsky and colleagues compared a spectrum of screen-related outcomes by age group in NLST to see if there were any systematic differences by age. There were data available from 19,210 participants aged younger than 65 and 7,110 aged older than 65. Patients in the older group were more likely to be former smokers and had a greater median pack-year history compared with the younger group.

Results showed that participants in the older group had higher rates of both positive and false-positive screens. In patients aged 65 or older, the rate of false positive was 27.7% compared with 22% in the younger group (P<.001). Additionally, the rates of invasive procedures after a false-positive screen were also slightly higher in the older group (3.3% vs. 2.7%; P=.039).

The researchers also found that the positive predictive value was higher in the older cohort (4.9% vs. 3.0%; P<.001). This was due to a higher prevalence of lung cancer in the older group (1.5% vs. 0.7%; P<.001).

“Screen detected cancers were treated similarly with curative resection in each age group,” Pinsky said. “The rate of surgical mortality was low in each group.”

Pinsky also pointed out a caveat, that the older population in the NLST was healthier and had fewer comorbidities than the overall U.S. population in that age group who would be eligible for LDCT screening. Therefore, he said, it is not clear whether these same findings would hold up with population screening. 

In an editorial that accompanied the article, Michael K. Gould, MD, MS, of Kaiser Permanente Southern California, wrote that this new evidence should help to inform both policy makers and physicians.

“For policymakers, LDCT screening seems to involve similar tradeoffs for persons who meet NLST eligibility criteria in both the older and younger age groups. Until there is new and direct evidence to the contrary, it does not seem reasonable to exclude persons aged 65 to 74 years from access to screening,” Gould wrote. “For clinicians, it will be helpful to provide age-specific estimates of benefits and harms when engaging patients in a process of shared decision making that enables each to weigh the tradeoffs and make an informed choice.”