The results of BMC Medicine——ctDNA detection can predict the PFS of brain metastases in patients with EGFR mutant lung cancer.

　　Recently, BMC Medicine reported the curative effect of three generations of EGFR-TKI furmonertinib on patients with brain metastases from EGFR mutant lung adenocarcinoma. The objective remission rate of Furmonertinib on brain lesions reached about 61.5%, and the median PFS of brain lesions reached 11.6 months and 19.3 months in 80mg and 160mg groups respectively.

　　However, in this study, we saw 132 patients with brain metastasis, and 119 patients underwent ctDNA detection ("Zhen 'an" technology) before treatment, and the dynamic monitoring of ctDNA was carried out. It should be said that this study is the largest sample size report on dynamic monitoring of ctDNA in patients with brain metastases from EGFR mutant lung cancer in China. Let's see what the analysis results will do for the diagnosis and treatment of patients with brain metastases from EGFR mutant lung cancer in the future.

　　▌ Result 1: In patients with other mutations (except EGFR) detected by ctDNA, the PFS of brain lesions is shorter!

　　Baseline ctDNA detection was performed in 119 patients in all dose groups. It was found that the median PFS of brain lesions in T790M mutant group was longer than that in T790M co-mutation group (co-mutation genes include PTEN,TP53,RB1, ALK, BRAF, ERB2, Kras, MET, RET, ROS 1): it did not reach vs 11.6 months; In the 80mg dose group, the same conclusion was reached. Compared with the T790M co-mutation group, the PFS of the median brain lesion did not reach vs 10.5 months. This result shows that the PFS of patients can be predicted by ctDNA detection, and the benefit duration of EGFR TKI in patients with EGFR and other gene mutations is shorter.

　　▌ Result 2: Patients with brain metastases received furmonertinib treatment, and the negative rate of ctDNA reached 80%.

　　Patients with baseline EGFR T790M were tested again after 6 weeks of treatment, and T790M mutation was not detected in 85% of patients. The clearance rate of EGFR mutation was 88% after 8 weeks of treatment in BENEFIT study [2], and the clearance rate of 85% after 6 weeks of treatment in this study highlighted the high sensitivity of ctDNA detection in Tung tree. The study further explored the correlation between EGFR zeroing and PFS of brain lesions, and found that the contrast mutation of patients in zeroing group still existed, and there was a better PFS of median brain lesions: 13.2 m vs 10.5 m, but it did not reach statistical significance.

　　▌ Result 3: A large sample size study on brain metastasis of EGFR mutant lung cancer, and the diagnostic comfort -ctDNA technology has been recognized repeatedly.

　　It should be said that brain metastasis is a common type of metastasis in patients with lung cancer, and it is also a metastatic site that has an important impact on patients' survival. The prognosis of brain metastasis is not only related to the adjustment of patients' treatment plan, but also related to the improvement of patients' quality of life. However, previous studies have also suggested [3] that there is significant tumor heterogeneity between the molecular pathological features of brain metastases and the primary lesions. Moreover, because of the high risk, patients with brain metastases rarely do biopsy to confirm the molecular diagnosis. At this time, non-invasive ctDNA detection can make up for the shortcomings. The detection results not only cover the molecular characteristics of primary tumor lesions, but also include the molecular panorama of brain metastases, which can bring prompt value for clinicians to make decisions on patient diagnosis and treatment.

　　This study is a large sample study of brain metastasis of EGFR mutant lung cancer at present. The used diagnostic comfort -ctDNA detection technology improves the accuracy of ctDNA detection from the whole detection process, and many clinical studies have been recognized repeatedly. A number of research data published in The Lancet Respiratory, BMC Cancer, TLCR and other well-known journals have repeatedly confirmed the accuracy and comprehensiveness of this ctDNA detection technology, and can be used to guide the whole process of accurate diagnosis and treatment of lung cancer and colorectal cancer patients.