Abstract Introduction: Insulin like growth factor receptor (IGF1R) is involved in the proliferation and metastasis of various cancers. However, the clinical significance of IGF1R in non-small cell lung cancer (NSCLC) remains to be unclear. In this study, we retrospectively evaluated the correlation between IGF1R expression and clinicopathological features of NSCLC. Method: A total of 782 specimens of NSCLC patients who underwent surgical resection of primary lung cancer between 2010 and 2019 at Osaka Metropolitan University Hospital was enrolled in this study. Immunohistochemical staining of IGF1R were performed, and the correlation between IGF1R expression and clinicopathological features of NSCLC, especially in recurrence free survival (RFS) and overall survival (OS), was evaluated. We also evaluated an association between IGF1R and programmed death ligand 1 (PD-L1) expression. Results: IGF1R expression was positive in 279 (35.8%) patients. IGF1R-positive group had significantly longer smoking histories (median smoking index, 1,000 vs 600, p <0.01) and a higher proportion of squamous cell carcinomas (35.1% vs 14.1 %, p <0.01). IGF1R-positive group also significantly expressed PD-L1 (24.4% vs 6.4%, p<0.01). IGF1R-positive group had significantly worse RFS (10-year recurrence-free rate; 42.7% vs 53.7%, p <0.01) and OS (10-year survival rate; 54.4% vs 67.3%, p <0.01). RFS and OS were significantly worse in the IGF1R-positive NSCLC patients at stage 0 and stage I (10-year recurrence-free rate; 49.0% vs 62.9%, p <0.01, 10-year survival rate; 57.4% vs 74.2%, p<0.01), but not in stage II (10-year recurrence-free rate; 52.0% vs 43.8%, p=0.68, 10-year survival rate; 63.4% vs 47.5%, p=0.95) and III (10-year recurrence-free rate; 20.7% vs 20.8%, p=0.77, 10-year survival rate; 38.3% vs 54.6%, p=0.18). IGF1R expression was associated with poorer RFS and OS in early-stage NSCLC. Conclusion: IGF1R is a predictor of poor prognosis in resected early-stage NSCLC. Citation Format: Hiroaki nagamine, Masakazu Yashiro, Megumi Mizutani, Akira Sugimoto, Yoshiya Matsumoto, Yoko Tani, Kenji Sawa, Kazuhiro Yamada, Hiroyasu Kaneda, Tetsuya Watanabe, Kazuhisa Asai, Satoshi Suzuki, Tomoya Kawaguchi. Insulin-like growth factor receptor predicts poor prognosis in early-stage non-small cell lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3635.