Original Abstract
BACKGROUND: Subsolid nodules (SSNs) and ground glass opacities (GGOs) are an increasingly common clinical problem. This unique subtype of lung adenocarcinoma poses a treatment dilemma as many can be safely monitored with radiographic observation alone and require no intervention. Improved understanding of the natural history and outcomes of patients with subsolid nodules is needed to improve clinical decision making and treatment recommendations. RESEARCH QUESTION: What is the natural history of growth, likelihood of treatment, and most likely cause of mortality in a comprehensive cohort of patients with subsolid nodules and ground glass opacities identified on chest CT scan? STUDY DESIGN AND METHODS: Natural language processing was used to identify all patients with subsolid nodules on outpatient chest CT scans in 2017 (n=17,276) in the Yale New Haven Health system. Manual chart review was performed for demographics, nodule size, growth on subsequent CT, treatment, pathology, and survival. RESULTS: A cohort of 322 patients were identified with 64% (n=207) non-solid nodules (pure GGO) and 36% (n=115) part-solid nodules. Over 5-years of follow-up, 81% of non-solid nodules remained non-solid and 19% developed a new solid component. Within 5-years, 19% (n=60) underwent treatment, with patients with part-solid nodules being more likely to undergo treatment than those with non-solid nodules (32% vs 11%, p<0.001). Five-year overall survival was 79.8%, with 98.4% 5-year subsolid nodule-related survival. Development of a new, second primary malignancy was common in SSN-patients, who were significantly more likely to die from a secondary primary cancer than their subsolid nodule at 5-years (8.43% vs 1.54%, p<0.001). INTERPRETATION: Patients should be reassured regarding the excellent survival associated with subsolid nodules. Most can be safely observed without intervention, particularly non-solid nodules or pure GGOs. Patients with subsolid nodules have high rates of developing multiple lung nodules and second primary lung cancer.