Clinical Outcomes after Upfront Surgery in Clinical Stage I-IIA Small Cell Lung Cancer.

Background: Upfront surgery followed by systemic treatment is recommended to treat clinical stage I-IIA small cell lung cancer (SCLC), but data on the clinical outcomes are sparse. Thus, this study evaluated the stage migration and long-term prognosis of surgically treated clinical stage I-IIA SCLC.

Methods: We retrospectively reviewed 49 patients with clinical stage I-IIA SCLC who underwent upfront surgery between 2000 and 2020. Additionally, we re-evaluated the TNM (tumor-node-metastasis) staging according to the eighth edition of the American Joint Committee on Cancer staging system for lung cancer.

Results: The clinical stages of SCLC were cIA in 75.5%, cIB in 18.4%, and cIIA in 6.1% of patients. A preoperative histologic diagnosis was made in 65.3% of patients. Lobectomy and systematic lymph node dissection were performed in 77.6% and 83.7% of patients, respectively. The pathological stages were pI in 67.3%, pII in 24.5%, pIII in 4.1%, and pIV in 4.1% of patients. The concordance rate between clinical and pathological stages was 44.9%, and the upstaging rate was 49.0%. The 5-year overall survival (OS) rate was 67.8%. No significant difference in OS was found between stages pI and pII. However, the OS for stages pIII/IV was significantly worse than for stages pI/II (p<0.001).

Conclusion: In clinical stage I-IIA SCLC, approximately half of the patients were pathologically upstaged, and OS was favorable after upfront surgery, particularly in pI/II patients. The poor prognosis of pIII/IV patients indicates the necessity of intensive preoperative pathologic mediastinal staging.