Prognostic Implications of the Predominant Histologic Subtype in Stage I Lung Adenocarcinoma: Lack of Association with Overall Survival Based on Multi-Aspect Survival Analyses

We aimed to investigate the prognostic role of the predominant histologic subtype classification of lung adenocarcinoma in the era of the eighth-edition staging system. A total of 587 patients with stage I adenocarcinomas (lepidic, n=46; acinar/papillary, n=484; solid/micropapillary, n=57) were assessed. The prognostic value of this subtype classification for overall survival (OS) was investigated with three multivariable analyses adjusted for the eighth-edition clinical T category and radiologic nodule type: the adjusted log-rank test, multivariable Cox hazard regression, and multivariable mixture cure model to evaluate long-term and short-term prognostic associations separately. In the adjusted log-rank test for pairwise comparisons, no evidence was found for differences in OS among the subtype classifications (p>.05). The histologic subtype was not an independent prognostic factor in either the Cox regression analysis (hazard ratio [HR] of acinar/papillary subtypes: 3.03; 95% confidence intertval [CI]: 0.4-22.59; p=0.28; HR of solid/micropapillary subtypes: 2.78; 95% CI: 0.34-22.37; p=.34) or the mixture cure model (cure probability model; odds ratio: 1.06 [95% CI: 0.38-2.95; p=.91]; failure time distribution model; HR: 0.94 [95% CI: 0.36-2.44; p=.89]). The prognostic implication of the predominant histologic subtype classification is not clear for stage I lung adenocarcinoma in the eighth-edition staging system.