Adjuvant chemotherapy for resected stage-ia lung adenocarcinoma with micropapillary histologic pattern

OBJECTIVES: The micropapillary pattern is a high-risk factor for postoperative recurrence in lung adenocarcinoma (LUAD), but the role of adjuvant chemotherapy (ACT) in stage IA LUAD with micropapillary pattern (LUADmp) after resection remains unclear. METHODS: From September 2017 to August 2020, in the phase II trial, resected stage IA LUADmp patients received ACT (pemetrexed and carboplatin), forming the ACT-group. While those meeting the trial criteria but declining ACT in the same period were designated as the SoC-group. Recurrence-free survival (RFS) was compared between groups using univariate and multivariate analyses. RESULTS: The number of patients in ACT-group and SoC-group was 81 and 75, respectively. Compared to SoC-group, patients in ACT-group were younger (60.0 years vs 64.0 years, p = 0.019), had a lower proportion of EGFR/ALK mutation (58.0% vs 78.7%, p = 0.006), and had a higher proportion of Spread Through Air Spaces (59.3% vs 40.0%, p = 0.016). At the cut-off date of January 31st 2025, the median duration of follow-up was 65.6 months. Five-year RFS in ACT-group met the prespecified primary end-point, and no significant difference was observed between ACT-group and SoC-group (ACT-group vs SoC-group: 88.9% vs 86.7%, log-rank p = 0.534). Multivariate analysis showed ACT could not predict RFS independently (HR, 0.865, 95% CI, 0.334-2.240, p = 0.765). CONCLUSIONS: ACT was not significantly associated with improved RFS for stage IA LUADmp patients postoperatively. This study was registered at ClinicalTrials.gov: NCT03351842.