Pulmonary Nodules, Lung Cancer Screening, and Lung Cancer in the Medicare Population

BACKGROUND: 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. RESEARCH QUESTION: How common are PNs in the Medicare population? What is the rate of lung cancer after detection of PNs? What is the relative proportion of early-stage lung cancer diagnosed after reporting of PNs vs through low-dose CT (LDCT) scan screening? STUDY DESIGN AND METHODS: Using the Surveillance Epidemiology and End Results Program-Medicare database, we defined two cohorts: those in the 5% sample with $ 12 months of Medicare Parts A and B coverage from 2014 through 2019 (5% sample cohort) and those with a diagnosis of lung cancer from 2015 through 2017 with coverage for the prior 18month period (lung cancer cohort). We defined PNs as chest CT scans with accompanying codes of 793.11 (International Classification of Diseases [ICD], Ninth Revision) or R91.1 (ICD, Tenth Revision) denoting a solitary PN. Patients in the lung cancer cohort were classified by whether they had undergone LDCT scan screening and whether they had a diagnosis of PN or neither (reference) within 18 months before diagnosis. We compared cancer stage and survival across groups. RESULTS: Of 627,547 patients in the 5% sample cohort, 5.0% demonstrated PNs over median of 5.0 years of follow-up. Cumulative 1- and 2-year lung cancer rates after initial PN diagnosis were 3.2% and 4.7%, respectively. Of 44,194 patients in the lung cancer cohort, 15.7%, 2.9%, and 81.4% were in the PN, LDCT scan, and reference groups, respectively. Of patients in the PN, LDCT scan, and reference groups, 58.1%, 50.3%, and 24.4% respectively, had disease of a localized stage. Among all patients with localized disease, 30.0% and 4.9% were in the PN and LDCT scan and groups, respectively. Three-year lung cancer-specific survival rates were 75.0%, 75.6%, and 49.4% for the PN, LDCT scan, and reference groups. INTERPRETATION: Patients with lung cancer who received a diagnosis after identification of PNs tended to have localized disease. Of all patients with localized disease, almost one-third had PNs that were diagnosed previously, compared with 5% of patients who had undergone LDCT scan screening. PNs represent a relatively common presentation of potentially curable lung cancer