Objective: To analyze the consistency of plasma circulating tumor DNA (ctDNA) and tumor tissue DNA in detecting KRAS/NRAS/BRAF/PIK3CA gene mutations in patients with advanced colorectal cancer, and to explore the factors affecting the consistency. Methods: Patients with advanced colorectal cancer who were treated in Zhongshan Hospital Fudan University from December 2018 to May 2020 were enrolled. The results of plasma and tissue gene detection, clinicopathological information and treatment were collected. The consistency and influencing factors of plasma and tissue KRAS/NRAS/BRAF/PIK3CA status were analyzed. Results: The patients enrolled in this study all received plasma gene detection. The mutation rates of KRAS, NRAS, BRAF and PIK3CA in plasma were 27.30%, 2.42%, 6.06% and 9.70%, respectively. Among them, 128 patients underwent tissue gene testing, and the mutation rates of KRAS, NRAS, BRAF and PIK3CA were 30.47%, 2.34%, 7.03% and 3.13%, respectively. The overall coincidence rate of KRAS/NRAS/BRAF/PIK3CA status by plasma and tissue was 62.50% (Kappa=0.200, P=0.023). Univariate analysis showed that the consistency of gene detection was higher in newly diagnosed untreated group and liver metastasis group, but lower in lung metastasis group. Conclusion: Our real-world study found that there are some differences in KRAS/NRAS/BRAF/PIK3CA status between plasma and tissue. Anti-tumor therapy and metastatic sites may be important factors affecting the inconsistency.
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