The clinical implications of TMB and the relationship between TMB and EGFR mutations in non-small cell lung cancer of Xuanwei, China.

e20512 Background: Xuanwei lung cancer is a type of non-small cell lung cancer that occurs in Xuanwei, southwest China. It is different from non-Xuanwei non-small cell lung cancer in many aspects. The key is that Xuanwei lung cancer does not currently have a recognized prognostic biomarker. The significant molecular difference between Xuanwei lung cancer and non-Xuanwei lung cancer is the mutation type and mutation ratio of EGFR. Are different mutations of EGFR related to the prognosis of Xuanwei lung cancer? What are the reasons for the difference between Xuanwei lung cancer and non-Xuanwei lung cancer? These are clinical issues that we are very interested in. In addition, tumor mutation burden (TMB) has been shown to be an effective biomarker for predicting the clinical outcome of multiple cancer types. However, its prognostic value in Xuanwei lung cancer remains unknown. Methods: The Formalin-Fixed Paraffin-Embedded (FFPE) tissues samples from 172 primary NSCLC patients who have underwent next-generation sequencing (NGS) in a laboratory accredited by the College of American Pathologists (CAP) and Clinical Laboratory Improvement Amendment (CLIA) (3D Medicines Inc., Shanghai, China) from June 2015 to October 2020 were analyzed. The written informed consent was obtained from all included patients. The postoperative follow-up data of all these NSCLC patients were collected. Results: The prognosis of Xuanwei lung cancer is better than that of non-Xuanwei (p < 0.05). Xuanwei is superior to non-Xuanwei mainly in EGFR-positive patients (p < 0.05). Among patients without EGFR mutations, there is no difference in the prognosis of Xuanwei lung cancer and non-Xuanwei lung cancer. Further analysis revealed that there is a difference in TMB levels between Xuanwei lung cancer and non-Xuanwei lung cancer. The TMB level in Xuanwei lung cancer is significantly higher than that in non-Xuanwei lung cancer (p < 0.05). EGFR mutations can be used as prognostic markers for Xuanwei lung cancer, and this is related to patients with EGFR mutations having higher TMB levels. Our research results indicate that EGFR mutation may help combine traditional clinicopathological risk factors to optimize risk stratification and guide treatment decisions. Conclusions: Xuanwei lung cancer is a special subtype of NSCLC with different molecular features and prognosis. Analysis of data in this area will lead to the development of precision treatment options for Xuanwei lung cancer.