Prognostic significance of metaplasia in adenocarcinoma of the lung: A National Cancer Database analysis.

e20085 Background: Pulmonary adenocarcinoma is a major subtype of non-small cell lung cancer (NSCLC), yet the impact of metaplasia within the tumor remains understudied. This study utilized the National Cancer Database (NCDB) to analyze the prognostic significance of metaplasia in pulmonary adenocarcinoma. Methods: Using the NCDB, we conducted a retrospective analysis on patients with lung adenocarcinoma from 2010 to 2017 and followed STROBE guidelines. Kaplan-Meier survival analysis and Accelerated Failure Time (AFT) model were used for estimation of survival outcomes. Covariates included age, sex, race, tumor grade, TNM stage, Charlson Comorbidity Index, insurance status, year of diagnosis, facility type, and treatment modality. Statistically significant variables from AFT were subgroup analyzed with multivariate logistic regression to identify the relative representation of these variables in metaplastic and non-metaplastic arms. Results: A total of 16,330,918 patients were included, with 16,302,690 (99.83%) diagnosed with non-metaplastic adenocarcinoma (NMAC) and 28,228 (0.17%) with metaplastic adenocarcinoma (MAC). The unadjusted median overall survival (mOS) was significantly lower in MAC (12.25 months) compared to NMAC (24.48 months, p < 0.05). After covariate adjustment, MAC was associated with worse survival (HR 1.2, 95% CI: 1.12–1.28, p < 0.01). Logistic multivariate regression analysis identified significant predictors of MAC. Grade 4 tumors had the highest odds (OR: 103.10; 95% CI: 51.45–206.61; p<0.01), followed by grade 3 tumors (OR: 20.05; 95% CI: 10.68–37.61; p<0.01). Patients with M1b stage disease (OR: 1.31; 95% CI: 1.13–1.52; p<0.01) and those with a Charlson-Deyo Score of 1 (OR: 1.18; 95% CI: 1.03–1.35; p<0.05) were also more likely to have MAC. In contrast, female patients (OR: 0.79; 95% CI: 0.70–0.90; p<0.01) TNM N3 stage patients (OR: 0.77; 95% CI: 0.62–0.95; p<0.05) were less likely to have metaplastic adenocarcinoma. Conclusions: Metaplastic adenocarcinoma was associated with significantly worse outcomes compared to non-metaplastic adenocarcinoma. High grade, advanced M1b stage, and burden of comorbidities partially explains these poor outcomes, however, further studies are needed to explore and delineate the underlying mechanisms driving the worse outcomes seen by metaplasia in pulmonary adenocarcinoma.