Early detection of lung cancer through management of pulmonary nodules (PNs) may reduce lung cancer mortality. We assessed the relationship between PNs and lung cancer.

How common are PNs in the Medicare population? What is the rate of lung cancer following detection of PNs? What is the relative proportion of early-stage lung cancer diagnosed following reporting of PNs versus through low-dose CT (LDCT) screening?

Using the SEER-Medicare database, we defined two cohorts: persons in the 5% sample with 12+ months of Medicare Part A&B coverage during 2014-2019 (5% sample cohort); subjects diagnosed with lung cancer during 2015-2017 with coverage for the prior 18-month period (lung cancer cohort). We defined PNs as chest CTs with accompanying codes of 793.11 (ICD-9) or R91.1 (ICD-10), denoting a solitary pulmonary nodule. Lung cancer cohort cases were classified by whether they had LDCT screening, PNs or neither (Referent) within 18 months before diagnosis. We compared cancer stage and survival across groups.

Of 627,547 5% sample cohort subjects, 5.0% had PNs over median 5.0 years follow-up. Cumulative 1- and 2-year lung cancer rates following initial PNs were 3.2% and 4.7%. Of 44,194 lung cancer cohort cases, 15.7%, 2.9% and 81.4% were in the PN, LDCT, and Referent groups. 58.1%, 50.3% and 24.4% of PN, LDCT and Referent group cases, respectively, were localized stage. Among all localized cases, 30.0% and 4.9% were in the PN and LDCT and groups, respectively. Three-year lung cancer-specific survival rates were 75.0%, 75.6% and 49.4% for the PN, LDCT, and Referent groups.

Lung cancer cases diagnosed following identification of PNs tended to be localized. Of all localized cases, almost one-third had prior PNs, compared to 5% with LDCT screens. PNs represent a relatively common presentation of potentially curable lung cancer.