First of all, people who have a family history of bowel cancer, here mainly refers to those who have immediate family members with colorectal cancer, especially those who have it in more than two consecutive generations and are under 50 years old, their offspring have a significantly higher risk of developing colorectal cancer, and the risk probability is nearly 20 times higher than that of the general population. Regular colonoscopy and tumor index tests related to bowel cancer are recommended. Secondly, those who have had malignant tumors themselves, especially those who have already suffered from bowel cancer, have about 10 times higher risk of suffering from bowel cancer than the general population. Here, it is especially reminded that women who have had cervical cancer and used radioactive local treatment have an increased chance of developing rectal cancer. It is recommended that these people should pay more attention to regular checkups and follow-ups after 5 years, in addition to regular follow-ups within 5 years after tumor surgery. The third group of people is patients with colon polyps, especially adenomatous polyps, which are precancerous in themselves, and close to 80% of colorectal cancers are transformed by adenomatous polyps. Therefore, patients with intestinal polyps should have their polyps removed in a timely manner, and they should have regular colonoscopy. The fourth group of people is those who are over 40 years old and have symptoms in the high-incidence area of colorectal cancer. The high incidence of colorectal cancer in China is mainly in the Yangtze River Delta region, the Pearl River Delta region and Hong Kong, Macao and Taiwan, with Suzhou, Zhejiang and Shanghai being the three areas with the highest incidence. The fifth group of people is patients with chronic ulcerative colitis, which can become cancerous due to the long-term stimulation of chronic inflammation in the large intestine. Therefore, patients with ulcerative colitis must pay attention to not only active treatment to strive to cure as soon as possible, but also for those who do not heal or recurring cases, may have to consider surgical removal of this “time bomb”. There is another group of people who come from schistosomiasis infected areas and suffer from schistosomiasis, because the dead schistosome eggs are deposited in the mucous membrane of the large intestine, which can cause cancerous changes after stimulation. Bowel cancer experts remind that gallbladder removal patients, diabetic patients and people with chronic constipation are not as risky as the aforementioned people, but according to research, they have a greater chance of getting bowel cancer than the general population.