Effect of invasive mucinous adenocarcinoma on lung cancer-specific survival after surgical resection: a population-based study

Baokground: In 2015, the World Health Organization (WHO) announced a new classification of lung tumors. Mucinous bronchioloalveolar adenocarcinomas were reclassified as invasive mucinous adenocarcinomas (IMAs). Due to the rarity or this tumor type, conflicting clinical outcomes have been reported based on small patient numbers. Methods: Patients diagnosed as primary lung nonmucinous adenocarcinoma (NMA) or IMA from 2000 to 2014 were extracted from the Surveillance, Epidemiology, and End Results (SEER) database. General features of each IMA were explored and the effect of histological characteristics on lung cancer-specific survival was analyzed in matched samples using the TNM staging system. Results: The incidence of IMA among all primary lung cancer patients was 0.2% (1,783/1,154,742), and the incidence of IMA among patients with a primary resected lung adenocarcinoma was 1.5% (531/35,406). IMAs tended to be located in the lower lobe (P<0.001), be well differentiated (P<0.001), and be NO (91.7% vs. 72.3%, P<0.001), T1 or T2 (P<0.001), and stage I tumors (P<0.001) when compared with NMAs. After matching by stages, a stratified Cox PH analysis revealed that the tumor histologic type (P=0.2) did not increase the risk of lung cancer-specific death, while advanced age (HR 1.03, P<0.(()1), male sex, and the need for radiation, pneumonectomy or sublobar resections increased the risk of cancer-specific death. Conclusions: The histologic type of the tumor, whether IMA or not, did not affect lung cancer-specific survival times among patients with a primary M0 stage lung adenocarcinoma. When stratified by the TNM staging system, patents that required pneumonectomy, sublobar resection or radiation had shorter lung cancer-specific survival times.