Elderly Get Most Benefit, Harm From Lung Cancer Screening

September 8, 2014
Dave Levitan
Dave Levitan

A new analysis of the NLST showed that both the benefits and harms of low-dose CT screening are slightly greater among patients older than 65 years.

A new analysis of the National Lung Screening Trial (NLST) showed that both benefits and harms of low-dose computed tomography (LDCT) screening are slightly greater among patients older than 65 years. This suggests that excluding elderly patients from screening is probably not warranted.

“The primary source of evidence for LDCT effectiveness was the NLST, and because only 25% of the NLST participants were aged 65 years or older at randomization, there were reservations about whether the overall NLST results could be applied to the Medicare-aged population,” wrote study authors led by Paul F. Pinsky, PhD, of the National Cancer Institute in Bethesda, Maryland. Pinsky’s group compared data from the NLST on those aged 65 years and above vs those aged less than 65 years; results will be published tomorrow in Annals of Internal Medicine. The main NLST analysis showed a reduction in lung cancer mortality in high-risk individuals between the ages of 55 and 74 years for LDCT vs chest radiography.

The new study found the aggregate false positive rate was higher in the older cohort, at 27.7% vs 22% in the younger group (P < .001). There were also more invasive diagnostic procedures following a false positive screening result, at 3.3% vs 2.7% (P = .039). Counterbalancing those harms, though, was an increased benefit as well: prevalence and positive predictive value (PPV) of screening were both higher in the elderly group. PPV was 4.9% for those over 65 years compared with 3% in the younger group.

Complications from invasive procedures were low in both groups, and not statistically different. The resection rates for screen-detected cancer were also similar, and, as one would expect, 5-year all-cause survival was lower in the older group of participants (55.1% vs 64.1%; P = .018).

These data add to an earlier analysis that showed an excess of 27.5 cancer deaths per 10,000 participants screened with chest radiography vs LDCT in the under-65 cohort, compared with 40.8 deaths per 10,000 participants in the older group. That yielded a number needed to screen to prevent 1 lung cancer death of 364 for younger people and 245 for the older participants.

In an accompanying editorial, Michael K. Gould, MD, of Kaiser Permanente Southern California in Pasadena, wrote that this shows there are similar tradeoffs for persons meeting the NLST eligibility criteria in both older and younger 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,” he wrote. Gould also noted that these data will let clinicians offer age-specific estimates of benefits and harms when helping patients make decisions.