Impact of the micropapillary component on the timing of recurrence in patients with resected lung adenocarcinoma.

Objectives A micropapillary (MIP) component is reported to be associated with a poor prognosis in patients with completely resected lung adenocarcinoma. The purpose of this study was to investigate the impact of an MIP component on the timing of postoperative recurrence using hazard curves. Methods A total of 1289 patients with lung adenocarcinoma who underwent complete pulmonary resection from 2008 to 2015 were studied. Hazard curves representing the changes in hazard over time were evaluated. Results The hazard curve displayed an initial wide, high peak within 1 year after surgery in patients with an MIP component, whereas some gentle peaks around the second year were noted in patients without an MIP component. The presence of an MIP component was associated with a worse recurrence-free survival and an early recurrence in stage I patients but not in advanced-stage patients. In multivariable Cox regression, the presence of an MIP component and lymph node metastasis, pleural invasion and gender were associated with a poor prognosis. Conclusions Patients with an MIP component retained a high risk of early recurrence after surgery, and the risk for recurrence persisted over the long term. Even after complete resection in stage I lung adenocarcinoma patients, an MIP component remains correlated with a poor prognosis.