Micropapillary Predominant Lung Adenocarcinoma in Stage IA Benefits from Adjuvant Chemotherapy

The benefit of adjuvant chemotherapy remains unknown for patients with stage IA micropapillary predominant (MPP) lung adenocarcinoma (ADC). This study investigated the effect of adjuvant chemotherapy in ADC and MPP patients in stage IA.

A total of 5220 stage IA lung ADC patients from SEER database and 152 MPP subtype patients from Qilu Hospital of Shandong University were retrospectively analyzed. Propensity score matching analysis was used to adjust the confounding factors. The benefits of improved overall survival (OS) or progression-free survival (PFS) from adjuvant chemotherapy in patients with resected stage IA ADC or MPP patients were investigated.

Based on SEER database, for ADC patients in stage IA, chemotherapy (no vs. yes: hazard ratio [HR]: 0.674, 95% confidence interval [CI] 0.474-0.958, P = 0.030), together with radiotherapy (no vs. yes: HR: 0.519, 95% CI 0.358-0.751, P = 0.001), race, gender, age, and T stage were all statistically significant independent factors for OS. However, in propensity model, there was no significant difference in OS between patients who received adjuvant chemotherapy and those who did not. Only age was a significant prognostic predictor for OS. For patients with MPP subtype in stage IA, multivariate analysis revealed that chemotherapy (no vs. yes: HR: 2.054, 95% CI 1.085-3.886, P = 0.027) as well as T stage were prognostic predictors for OS. Chemotherapy (no vs. yes: HR: 2.205, 95% CI 1.118-4.349, P = 0.022) and T stage also were significant predictors for PFS.

Adjuvant chemotherapy is a favorable prognostic factor for MPP patients in stage IA but not for lung ADC patients. MPP subtype could benefit from adjuvant chemotherapy.