Prognostic impact of lung adenocarcinoma second predominant pattern from a large European database

Background and Objectives: Adenocarcinoma patterns could be grouped based on clinical behaviors: low- (lepidic), intermediate- (papillary or acinar), and high-grade (micropapillary and solid). We analyzed the impact of the second predominant pattern (SPP) on disease-free survival (DFS). Methods: We retrospectively collected data of surgically resected stage I and II adenocarcinoma. Selection criteria: anatomical resection with lymphadenectomy and pathological N0. Pure adenocarcinomas and mucinous subtypes were excluded. Recurrence rate and factors affecting DFS were analyzed according to the SPP focusing on intermediate-grade predominant pattern adenocarcinomas. Results: Among 270 patients, 55% were male. The mean age was 68.3 years. SPP pattern appeared as follows: lepidic 43.0%, papillary 23.0%, solid 14.4%, acinar 11.9%, and micropapillary 7.8%. The recurrence rate was 21.5% and 5-year DFS was 71.1%. No difference in DFS was found according to SPP (p =.522). In patients with high-grade SPP, the percentage of SPP, age, and tumor size significantly influenced DFS (p =.016). In patients with lepidic SPP, size, male gender, and lymph-node sampling (p =.005; p =.014; p =.038, respectively) significantly influenced DFS. Conclusions: The impact of SPP on DFS is not homogeneous in a subset of patients with the intermediate-grade predominant patterns. The influence of high-grade SPP on DFS is related to its proportion in the tumor.