Clinical Study of Gastric Cancer, Colorectal Cancer and Bladder Cancer Based on Liquid Biopsy

Gastric cancer and colorectal cancer are common gastrointestinal malignancies in the world.Early cancer generally has no obvious symptoms. Endoscopy is the "gold standard"for the diagnosis of gastric cancer and colorectal cancer.gastric cancer and colorectal cancer treatment mainly includes surgery and medication.Compared with traditional diagnosis and treatment methods, the application of gene detection technology, especially high-throughput sequencing technology (NGS) in tumor diagnosis and treatment, performs multi-dimensional and multi-target detection of cancer-related genes, which can quickly and accurately determine the target gene mutations Morphology and expression differences, so as to provide personalized guidance to patients in terms of medication, treatment or prognosis evaluation, which can save a lot of time and treatment costs, and improve the overall treatment effect and patient quality of life. Cystoscopy and biopsy sampling pathological testing are the gold standard for bladder cancer diagnosis, and have been widely used in clinical diagnosis and prognosis judgment. However, cystoscopy is cumbersome, expensive, and often causes pain to the patients under test. At present, the main clinical non-invasive detection technique for bladder cancer is still the cytological examination of urinary tract bladder cells in urine, and its sensitivity and specificity are not good, especially for the diagnosis of early lower grade bladder cancer.For bladder cancer, tumor tissue (puncture biopsy or surgical resection) DNA, urine ctDNA, urinary tract exfoliated cell DNA and peripheral blood ctDNA can be used for genetic testing, but the consistency of the genetic testing results of these four types of samples has not been verified, especially There is no systematic evaluation of the guidance effect of non-invasive gene detection of free tumor DNA and urinary tract shed cell DNA in the diagnosis and treatment of bladder cancer.The corresponding relationship between the significant mutation genes contained in the DNA derived from bladder urinary tract cancer and the various types and stages of bladder cancer is not clear.