Effect of Micropapillary Pattern and Spread through Air Space in Patients with Lung Adenocarcinoma ≤ 2 cm

Objective: To analyze the relationship between micropapillary pattern (MIP) and tumor spread through air space (STAS) and postoperative survival rate in patients with lung adenocarcinoma ≤ 2 cm. Methods: Retrospective analyses were performed on clinical data of 575 patients with lung adenocarcinoma ≤ 2 cm, which were resected from 2009 to 2011. We analyzed the pathological findings on the resected specimens, with special reference to the presence/absence MIP and STAS, which have been reported to be a marker of poor prognosis of lung adenocarcinoma. Patients were divided into three according to the presence/absence of MIP and STAS: low-risk (MIP- STAS-), medium-risk (either MIP or STAS + (one plus)) and high-risk group (+/+: double plus). Endpoint was postoperative survival rate, which was compared among three groups. Results: There was no statistical difference in age, sex, and serum CEA level among three groups. In lobectomized patients, there was no statistical difference in prognosis among three groups;however, in sub-lobectomy group, patients with double + (+/+ for MIP and STAS) showed a lower survival rate than others (P < 0.001). Conclusion: The presence of MIP and STAS reduced the survival rate in sub-lobectomized patients.