The significance of early diagnosis of intestinal malignant tumors Colorectal cancer, including colon and rectal cancer, is one of the fastest growing tumors in most countries and regions in the world in the past two to three decades in terms of the number of incidence and death. Recent epidemiological data show that colorectal cancer has risen to be the third most common cancer worldwide, with 700,000 people suffering from colorectal cancer and 500,000 dying from it in 2000. In China, colorectal cancer is also one of the common tumors, and its incidence and mortality rate are the highest in the middle and lower reaches of Yangtze River where economic development is rapid. According to the statistics of Shanghai, the initial incidence rate of colorectal cancer was 2812/100,000 people in 1990, and reached 4018/100,000 people in 2000, which is 211 times of that in 1979, and its incidence rate ranks the third among male malignant tumors (4014/100,000), after lung cancer and stomach cancer; it ranks the second among women (4113/100,000), after breast cancer. With the development of economy, improvement of living standard and change of lifestyle, the incidence rate of colorectal cancer will continue to show a rising trend. In 2005, the 5-year survival rates of young patients aged 20-40 years with stage I, II, III and I V rectal cancer treated from 1991 to 1999 were 87.19%, 75.14%, 51.13% and 8.10%, respectively, while the 5-year survival rates of elderly patients aged 60-80 years with rectal cancer were 91.19%, 69.18% and 10.5%, respectively. The 5-year survival rates for elderly rectal cancer patients aged 60-80 years were 91.19%, 69.18%, 52.18%, and 6.16%, respectively. Therefore, early diagnosis and early treatment of colorectal cancer are of great significance to prolong the survival time and reduce the mortality rate of patients. Second, the technology of early diagnosis of intestinal malignant tumors 1, high-risk groups and screening 2, screening of high-risk groups of colorectal cancer China’s colorectal cancer screening target: family history of familial adenomatous polyposis and hereditary non-polyposis colorectal cancer members over 20 years old; adults over 40 years old without family history of tumors. The recommended screening protocol for sporadic colorectal cancer is: (1) positive immunological fecal occult blood test; (2) first-degree relative with colorectal cancer; (3) history of cancer or intestinal polyps; (4) two or more of the following: chronic constipation, chronic diarrhea, mucus and blood stools, history of adverse life events (e.g., divorce, death of a close family member, etc.), chronic history of appendicitis. For those who are found to have abnormalities, they should be treated according to the treatment principle, and those who are negative should be rechecked once a year for fecal occult blood test (FOBT). (1) Fecal occult blood test (FOBT) is an effective means of clinical examination and the most common method for screening colorectal cancer. At present, reverse indirect hemagglutination method (RPHA) is commonly used at home and abroad, and its sensitivity and specificity are very strong. The application of anti-human hemoglobin antibody immunoassay for occult blood test is not interfered by animal blood in food or iron and other drugs, which can reduce false positive results. (2) Rectal finger examination is the most important method to diagnose rectal cancer, because more than 75% of Chinese rectal cancer is low rectal cancer, they can be touched during rectal finger examination. Therefore, anyone who has symptoms such as blood in stool, change of stool habit and deformation of stool should have rectal finger examination in time. Endoscopy (1) General electronic colonoscopy Electronic colonoscopy is the most commonly used examination technology, which can directly observe various lesions of colorectal mucosa, such as mucosal congestion, erosion, polyps, ulcers, masses, etc. The characteristic manifestations of malignant tumors are brittle and brittle. Early colorectal cancer, especially flat type tumors, lack of specific signs are easy to miss diagnosis. (2) Pigmented endoscopy Pigmented endoscopy refers to the use of pigmented preparations and dyes to increase the contrast between lesions and normal tissues on the basis of conventional endoscopic examination, so as to make the morphology and scope of lesions clearer, thus improving the visual detection of gastric cancer, guiding biopsy and treatment, and increasing the detection rate of lesions. (3) Magnification endoscopy Magnification endoscopy can magnify the endoscopic image tens to hundreds of times, which can clearly show the microstructural changes such as the opening of glandular ducts and microvasculature in the mucosa of the digestive tract. （EUS can also be used to determine the presence or absence of regional lymph node metastasis. EUS can also be used to accurately stage gastric cancer to guide treatment and for postoperative follow-up to detect residual or recurrent cancer. Due to the limitation of ultrasound beam penetration distance, the large part of the right lobe of the liver, the retroperitoneum and mesenteric lymph nodes below the superior mesenteric vessels in the abdominal cavity cannot be detected by EUS, so EUS cannot provide conclusive diagnosis of distant metastases. (5) Fluorescence endoscopy The principle is that compounds in biological tissues react with luminescent substances of specific wavelengths and can emit special fluorescent signals. The biochemical characteristics of benign and malignant lesions are different, and the corresponding fluorescence spectra have specificity. Fluorescence endoscopy can clearly show early tumors in the gastrointestinal tract and the degree of mucosal infiltration, but is not as specific for superficial tumors. Autofluorescence endoscopy has strong advantages in guiding biopsy. (1) Colon gas-barium enema imaging For patients suspected of colon and rectal cancer, double contrast gas-barium imaging is feasible, which can show a mass in the intestinal cavity with irregular corridors and disappearance of mucosal folds. The lesion mostly occurs on one side of the intestinal wall, with irregular shape and uneven edges, and there are often different degrees of filling defects around the niche. Endoscopic examination is required when there are suspicious findings. (2) CT Spiral CT has a certain value in the diagnosis of intestinal tumor, which can better observe the situation inside and outside the gastrointestinal tract and whether there is metastasis in distant organs, and has unique diagnostic effect on intestinal tumor that grows mainly outside the wall or between the walls, which is obviously better than endoscopy and gastrointestinal imaging. Spiral CT can improve the detection rate of intestinal tumors (especially early tumors) and accurate tumor staging by relying on the changes of intestinal wall thickness, abnormal enhancement and thickening, and mucosal changes. (3) MRI Modern MRI machines use fast spin-echo technology and respiratory compensation method to scan under non-breath-holding condition, which can overcome motion artifacts to the greatest extent and improve image quality significantly. MR (magnetic resonance) colon imaging is also an emerging technique for colorectal cancer screening, which has all the advantages of MR, such as no radioactivity and the ability of multi-planar imaging. Clinical application of tumor marker detection Currently, tumor markers have great value in clinical application, because the content of tumor markers in patients’ serum often has a direct quantitative relationship with the growth and regression or metastasis of tumor tissues. The detection of a significantly elevated tumor marker in serum by immunological or biochemical methods will facilitate the diagnosis of the tumor, the identification of high-risk groups, and the implementation of group follow-up surveillance. Some tumor markers can also provide targets for clinical immunoimmunoassay targeting and directed therapy. Studies of oncogenes and oncogenes have shown that detection of alterations in certain oncogenes or oncogenes in tissue cells can be used for early diagnosis and prognostic assessment of tumors, and can also provide directions for gene therapy of tumors. At present, there are hundreds of tumor markers available for clinical application, now we will briefly introduce the common tumor markers in digestive system. (1) Serum tumor markers can be divided into embryonic antigens (such as methemoglobin, carcinoembryonic antigen); tumor-related glycolipid and glycoprotein antigens (such as CA1929, CA7224, CA1225); antigens expressed in normal tissues but overexpressed in tumor tissues, or antigens excreted when tumor cells divide or break down (such as ferritin, alkaline phosphatase); tumor-specific growth factors (such as ferritin, alkaline phosphatase). Angiogenic factors are released during the formation and growth of malignant tumors). (2) Molecular markers The results of oncogene studies have shown the potential of certain molecular level tests for diagnosis and early monitoring of tumorigenesis and prognosis determination. Telomerase is a ribonucleoprotein that may catalyze the synthesis and maintenance of a certain sequence of telomeres (composed of shorter DNA repeats and associated proteins). The activation of telomerase maintains the length of telomeres at a certain dynamic equilibrium, allowing the cells to proliferate malignantly without restriction, thus leading to the development of tumors. Molecular markers associated with GI tumors include oncogenes (e.g., P53, LOH 1/P53, LOH8P); oncogenes (e.g., K 2ras, C2myc, erbB2); apoptosis-related genes (e.g., Bcl22, BAX); DNA synthesis-related genes (e.g., thymidylate synthase); transforming growth factor (TGF) and epidermal growth factor receptor ( EGF2R) and genes (e.g. TGF22, TGF2β, EGF2R); cell cycle-dependent kinase inhibitor genes (e.g. P27, P21); adhesion molecule and glycoprotein genes (CD44, calmodulin); metastasis inhibitor genes (nm232H1). (3) Fecal exfoliated cells and DNA examination Fecal colorectal exfoliated cytology test: normal colorectal mucosa exfoliated mainly apoptotic cells, while colorectal cancer tissues exfoliated mainly a large number of cytokeratin immunohistochemical staining positive colon cells and inflammatory cells, the exfoliated colon cells still retain the characteristics of expressing tumor-related antigens. Colorectal exfoliated epithelial cells in stool are collected for routine pathological examination and have a high specificity for the diagnosis of malignant tumors. DNA markers in fecal colorectal exfoliated cells: Detection of genetic mutations in fecal exfoliated tumor cells is a promising emerging non-invasive screening technique for colorectal cancer screening. DNA can exist stably in feces and is continuously shed from colorectal mucosa, and trace DNA in feces can be detected by polymerase chain reaction (PCR) and other amplification techniques, which is a good marker. The chromosome ploidy and nuclear DNA content of normal somatic cells are constant, while the chromosome number and DNA content of malignant tumor cells are increased in most cases. There are many advantages of screening colorectal cancer by detecting mutations in fecal shedding cells: ① the mutations detected are more specific for colorectal cancer; ② the marker is constant, DNA is continuously shed from colorectal cancer and precancerous tissues, and only one fecal specimen is needed for analysis; ③ high sensitivity and specificity; ④ better compliance; ⑤ low false-positive rate; ⑥ the shedding cells from any part of the colorectum can be detected The ability of detecting proximal colon cancer has been enhanced. Most of these tumor markers are still in the research and observation stage. In the future, they may be expected to be used as tools for diagnosis, prognosis and adjustment of treatment plans in clinical oncology. The ideal tumor marker should be highly sensitive and specific, and can be used for disease follow-up and treatment response to assess prognosis, and help detect metastasis and recurrence at an early stage, none of which has such superior characteristics so far. However, there may be more than one marker for the same tumor, and the same marker may be present in different tumors. This feature provides a flexible and diverse combination of clinical options for highly sensitive or specific detection of a particular type of tumor. For a specific tumor measurement, several indicators with high specificity can be selected at the same time to complement each other and improve the positive rate of diagnosis. 7.Pathological diagnosis This examination is the basis for final diagnosis of colorectal cancer, and multiple sampling during endoscopy can improve the accuracy of diagnosis. The depth of infiltration and the relationship with the surrounding area are affected by the depth of sampling and need to be combined with other means for comprehensive analysis. Since the prevalence of intestinal malignancy in China is increasing, and the early and late treatment is directly related to the effect of treatment and survival time, it is important for patients and related people to pay attention to the understanding of this disease, and to understand the knowledge related to this disease, so as to strive for early diagnosis, early diagnosis and early treatment. Medical workers should be more alert to the malignant tumor of intestine, so that no symptomatic patient will be missed, and recognizing the related symptoms and timely examination is the key to early diagnosis. Regular screening and re-examination of high-risk groups is also one of the effective measures to improve early diagnosis. Due to the inherent shortcomings of screening technology, it is still necessary to combine multiple screening technologies to complement each other in order to improve the diagnosis of early intestinal malignancies. We believe that with the continuous development of China’s economy and health care, the early detection rate of intestinal malignant tumors will be greatly improved, and the standardized treatment of intestinal malignant tumors will also be improved day by day. These will definitely bring good news to the patients.