Adjuvant chemotherapy in patients with recurrence after completely resected stage IB lung adenocarcinoma: Propensity-matched analysis in a cohort of 147 recurrences

Background: Adjuvant chemotherapy (ACT) is considered for high-risk patients in stage IB lung adenocarcinoma (LUAD). However, these risk factors are recognized as negative prognostic factors, not as predictors of ACT efficacy. This study aimed to analyze the efficacy of ACT in stage IB patients by retrospectively examining patients who had recurrence. Methods: We reviewed 1399 patients with stage IB (American Joint Committee on Cancer 7th edition) LUAD from 2012 to 2017 in our institution and found 147 patients with recurrence. The last follow-up date was December 30, 2021. One-to-one propensity-score matching (PSM) was used to reduce the potential selection bias. Results: Fifty-five (37.4%) patients had received ACT and 92 (62.6%) had not (nonACT). Patients with ACT were younger (p < 0.001), had larger tumors (p < 0.001) and more lymphovascular invasion (p = 0.02), and seemed to have less distant recurrence (p = 0.001). After PSM, 110 patients were matched and baseline characteristics were balanced. ACT was not associated with improved disease-free survival (DFS) after matching (mDFS = 23.5 m for ACT vs. 29.5 m for non-ACT, p = 0.13). ACT failed to prolong DFS of patients in the extracranial recurrence subgroup and EGFR mutation subgroups, and was even associated with shorter DFS in intracranial relapsed patients (mDFS = 30.3 m vs. 33.5 m, p = 0.083) and patients with tumor <= 30 mm (mDFS = 21.9 m vs. 30.8 m, p = 0.076). Conclusion: In patients who were destined to develop recurrence after completely resected stage IB LUAD, ACT might not be associated with improved DFS. Further large multicenter studies are warranted to validate these findings.