Noncalcified nodules conveyed long-term lung cancer risk and acted as cancer precursors, according to study results.
The findings “offer support to the idea of utilizing noncalcified nodules as substitute outcomes for chemoprevention,” the researchers concluded.
Paul Pinsky, PhD, of the division of cancer prevention at the NCI and NIH, and colleagues pooled data from the National Lung Screening Trial (NLST) to identify whether noncalcified nodules seen on baseline low-dose CT are associated with increased long-term risk for lung cancer. They then compared the risk for lung cancer with the known increased short-term risk associated with noncalcified nodules.
The study included 26,272 patients from the low-dose CT arm of the NLST. Patients received a low-dose CT screen at baseline and two additional screens thereafter. Researchers analyzed lung cancer incidence at the person, lung and lobe levels relative to the location of the noncalcified nodules.
Median follow-up was 6.5 years.
Researchers observed 468 lung cancer cases short term (baseline to 23 months), 413 cases medium term (24 months to 59 months) and 190 cases long term (60 months to 84 months).
Patients with noncalcified nodules had a significantly increased long-term cancer risk at the person level (RR=1.8), lung level (RR=2.4) and lobe level (RR=3.5). Short-term RRs were 10.3 at the person level, 16.8 at lung level and 38 at the lobe level.
Researchers observed a positive association with ground glass attenuation and long-term lung cancer risk, but an inverse association between ground glass attenuation and short-term risk.
The size of the noncalcified nodule was positively associated with short-term risk but was not significantly associated with long-term risk, according to researchers.
“That noncalcified nodules convey significantly elevated excess long-term [risk] of lung cancer lends evidence to the hypothesis that some noncalcified nodules may be cancer precursors,” Pinsky and colleagues wrote.
Disclosure:The study was funded by the NCI.