B80-4-13 Diagnostic Evaluation and Clinical Outcomes Among Adults With High-risk Subsolid Pulmonary Nodules

Rationale Subsolid nodules (SSNs) have increased cancer risk compared to solid nodules but often represent more indolent adenocarcinoma spectrum disease, making management challenging. We sought to determine contemporary real-world SSN management and clinical outcomes at a large U.S. health system. Methods We performed a retrospective cohort study among adults at Penn Medicine with ≥1 SSN identified on a positive lung cancer screen (Lung-RADS 3, 4A, 4B/4X) between 2008-2021 and ≥12 months of follow-up. From the time SSNs first met positive screen criteria until last available follow-up, we collected detailed clinical data via manual chart and imaging review. We used descriptive statistics, chi-squared, and Kruskal-Wallis tests to assess differences in adherence to recommended follow-up (Lung-RADS 3: 4-9-month CT chest; 4A: 1-5-month CT chest or PET/CT; 4B/4X: 0-5-month CT chest, PET/CT, or biopsy), rates of diagnostic procedures, and lung cancer diagnoses by baseline Lung-RADS score. We compared median overall survival between those with and without lung cancer. Results Among 127 adults with high-risk SSNs (median age, 66 years [IQR, 62-70]; 34% Black race; 32% currently smoking) with Lung-RADS scores of 3 (50%), 4A (29%), and 4B/4X (21%), 20 (16%) and 107 (84%) had dominant ground-glass and part-solid SSNs, respectively. Adherence to recommended follow-up increased with Lung-RADS score (3: 47%, 4A: 62%, 4B/4X: 77%; P=0.03). Over median follow-up of 64 months (IQR, 48-87), 95% of individuals had follow-up CT chest imaging, 47% PET/CT imaging, and 30% invasive diagnostic procedures (10% bronchoscopy, 10% transthoracic needle biopsy [TTNB], and 19% surgical lung resection). Rates of PET/CT (P<0.001), TTNB (P=0.01), and surgery (P<0.001) increased with increasing Lung-RADS scores. Among 24 patients undergoing surgical resection, 2 (8%) were diagnosed with benign conditions. Overall, 38 (30%) patients were diagnosed with lung cancer (median time to diagnosis, 21 months [IQR, 6.6-41]), 28 (74%) with pathological confirmation. Lung cancer rates increased with Lung-RADS score (3: 16%, 4A: 30%, 4B/4X: 65%; P<0.001). Most cancers were diagnosed at early stage (84%) via surgical resection (68%) regardless of Lung-RADS score. Twenty-two (17%) patients died during follow-up (median time to death, 64 months [IQR, 48-87]), of whom 14 (64%) had a lung cancer diagnosis. Median overall survival did not differ between those with and without a lung cancer diagnosis (62 vs 64 months; P=0.6). Conclusion In this cohort study of adults with high-risk SSNs, 30% were diagnosed with lung cancer, 84% at early stage, and there was no difference in median overall survival. This abstract is funded by: Research reported in this abstract was supported by the National Cancer Institute (K08CA279881).