Comparative survival outcomes among histological subtypes of pulmonary adenocarcinoma: A nationwide study.

e20066 Background: Adenocarcinoma of the lung is a heterogeneous malignancy with multiple histological subtypes. In the US, population survival outcomes across these subtypes remain underexplored. Methods: A retrospective analysis of patients with various Lung Adenocarcinomas (Acinar, Lepidic, Papillary, Solid & solid type, Invasive mucinous, Mixed mucinous/non-mucinous, Colloid, Fetal, and Enteric type), diagnosed between 2010 and 2017, was conducted using the National Cancer Database in accordance with STROBE guidelines. Unadjusted median overall survival (mOS) was estimated using Kaplan-Meier survival analysis. Multivariate regression analysis was performed using accelerated failure time model to estimate covariate-adjusted hazard ratios (HR). Covariates included age, sex, race, tumor grade, TNM stage, Charlson Comorbidity Index, insurance status, year of diagnosis, facility type, and treatment modality. Lepidic carcinoma served as the reference arm for HR calculations. Results: A total of 46,218 patients were included in this large cohort study. 39,865 patients (86.3%) were white, 27,094 (58.6%) were female, 31,827 (69%) were aged ≥65 years, 29,843 (64.57%) had Medicare insurance, and 18,788 (40.65%) were treated in academic or research institutions. For unadjusted mOS, Acinar adenocarcinoma (n=15,877; 34.35%) demonstrated the best outcomes (mOS: 97.84 months, p<0.05). After covariate adjustment, Solid adenocarcinoma (n=1,736; 3.76%) had the most favorable prognosis (HR = 0.85, p<0.01). In contrast, Enteric type adenocarcinoma (n=33; 0.07%) exhibited the poorest survival, with an mOS of only 27.24 months (HR = 1.63, p<0.05). Lepidic adenocarcinoma (n=8,923; 19.31%), the reference group, demonstrated an mOS of 73.03 months with HR of 1. Other subtypes, such as Mixed/non mucinous adenocarcinoma (n=195; 0.42%; mOS: 85.22 months, HR = 0.91, p = 0.377) and Papillary adenocarcinoma (n=6,094; 13.19%; mOS: 64.79 months, HR = 0.97, p = 0.236), showed intermediate survival, with no statistically significant differences. On the other hand, significant differences were observed for Fetal adenocarcinoma (n=46; 0.10%; mOS: 39.82 months, HR = 1.17, p = 0.467), Invasive mucinous adenocarcinoma (n=1,254; 2.71%; mOS: 51.81 months, HR = 1.17, p<0.01), and Colloid adenocarcinoma (n=12,060; 26.09%; mOS: 44.09 months, HR = 1.29, p<0.01). Conclusions: This study highlights marked differences in survival across lung adenocarcinoma subtypes. These results stress the importance of further research to develop therapies tailored to specific histological variants. Adenocarcinoma subtype HR CI P value Lepidic ref Acinar 0.90 0.86–0.94 <0.01 Solid 0.85 0.78–0.92 <0.01 Enteric type 1.63 1.05–2.53 <0.05 Mixed/non mucinous 0.91 0.75–1.11 0.37 Papillary 0.97 0.93–1.02 0.23 Fetal 1.17 0.78–1.74 0.46 Invasive mucinous 1.17 1.08– 1.26 <0.01 Colloid 1.29 1.24–1.34 <0.01