Immunochemotherapy as induction treatment in Stage III (N2, N3) Non-small cell lung cancer

Background: To increase locoregional and systemic tumor control, a portion of patients with stage III (N2, N3) non-small cell lung cancer (NSCLC) received pulmonary resection after immunochemotherapy in our center. Herein, we assessed the real-world downstage (T, N stage) effectiveness of induction immunochemotherapy and explored the proper cycle number for stage III (N2, N3) NSCLC. Methods: Biopsy confirmed stage III (N2, N3) NSCLC patients underwent induction immunochemotherapy between January 1st, 2018, to August 30th, 2019, were retrospectively identified. Tumor radiologic regression, lymph node down-staging, and pathological response information were collected. Results: In total, 16 patients with stage IIIA NSCLC, 30 with stage IIIB NSCLC, 9 with stage IIIC NSCLC (N2, N3 metastasis) were included. After immunochemotherapy, 25/55 (45.5%) patients achieved an objective response. Ultimately, 33/55 (60.0%) patients received lobectomy plus systemic lymphadenectomy, of whom 18/33 (54.5%) obtained major pathological response (MPR) of the primary lesion, and 24 (72.7%) had pathological-confirmed lymph node downstage (N2-3 to N0-1). Notably, four patients had MPR of the primary lesion but without lymph node downstage. At the data cutoff time (December 30th, 2020), the median follow-up duration was 9.2 months (IQR 8.0-11.7), 24/33 (72.7%) of patients that had surgery were progression-free, with 30 of them alive. Binary logistics analysis showed that 3-4 induction cycles were favorably associated with MPR than 1-2 cycles (p = 0.017). Conclusions: Induction immunochemotherapy showed encouraging MPR and nodal down-staging rates in stage III (N2, N3) NSCLC in this study. Prolonged (3-4) cycles of immunochemotherapy were recommended for better pathological response.