Colorectal cancer, including colon cancer and rectal cancer, is a high-risk gastrointestinal malignant tumor, and the incidence rate has taken the fourth place among common tumors, after lung, stomach and liver cancer, and the rising trend of incidence rate is very obvious in recent years. According to statistics, the rate of increase of incidence in China far exceeds the international level of 2%, and is directly approaching 5%. The high incidence age of colorectal cancer in China is above 50 years old. However, in recent years, the proportion of young people suffering from colorectal cancer has been rising, and there are more men than women. So what are the causes of colorectal cancer? 1, dietary factors: It is generally believed that high animal protein p high fat and low fiber diet are the factors of high incidence of colorectal cancer. 2, genetic factors: family members with family history of colorectal cancer have 2-6 times higher risk of developing colorectal cancer than the general population. Some genetic diseases are prone to colon cancer: familial polyposis, Turcot syndrome, Gardner syndrome, juvenile polyposis, Cowden’s disease, etc. 3.Ulcerative colitis, colonic polyposis, colonic adenoma, schistosomiasis, etc.: these diseases are precancerous lesions of colon, and their precancerous course is 5-20 years. 4.Age: The average age of colon cancer patients is between 60-65 years old. The older the age, the greater the risk of colon cancer. Other factors: lack of molybdenum, lack of selenium, frequent exposure to asbestos, constipation, low stool volume, increased number of anaerobic bacteria in the intestinal cavity may also be related to the occurrence of colon cancer. So what are the symptoms of colorectal cancer? Generally speaking, there are no symptoms in the early stage of colorectal cancer, but some patients may have changes in stool habits, such as normal stool but suddenly constipation or diarrhea, another situation is frequent constipation but suddenly diarrhea recently, blood in stool is an important clinical manifestation. Clinically, when colorectal cancer is detected, most of them are already in advanced stage. Thus, the prevention and early detection of colorectal cancer are crucial. Everything is done in advance, but not in advance. Science shows that as long as we can prevent early, we can reduce the incidence of colorectal cancer. Primary prevention 1. Dietary adjustment to reduce energy intake, especially the intake of high-fat and high-protein foods; increase the intake of fruits, vegetables and dietary fiber; 2. Changing living habits to strengthen physical exercise, prevent obesity, quit smoking and alcohol; 3. Treating precancerous lesions. Patients with colorectal adenoma and ulcerative colitis have significantly increased the incidence of colorectal cancer. Through screening and follow-up, early removal of adenoma and treatment of colitis can reduce the incidence and mortality of colorectal cancer. Especially for those with family history, screening high-risk groups through genetic examination and performing e-colonoscopy are important aspects of colorectal cancer prevention. Secondary prevention Secondary prevention of tumor, i.e. early detection, early diagnosis and early treatment to prevent or reduce death caused by tumor. The occurrence and development of colorectal cancer is a relatively long process, from precancerous lesions to invasive cancer, which is estimated to take 10~15 years, which provides opportunities for census to detect early lesions. The main means of screening are fecal occult blood test and colonoscopy. Census is an important tool for secondary prevention. Tertiary prevention Active treatment for tumor patients in order to improve patients’ quality of life and prolong survival. At present, surgery is the main treatment for colorectal cancer patients, supplemented by appropriate chemotherapy, Chinese medicine treatment and immunotherapy. Those with advanced colorectal cancer who have intestinal obstruction and cannot be operated can have stents implanted under colonoscopy to alleviate the symptoms of constipation and improve the quality of survival.