Due to factors such as environmental pollution and food safety, the incidence of colorectal cancer has risen to the fourth place of malignant tumors with the median age group being about 45 years old, with those under 40 years old accounting for about 1/3 of all cases and those under 30 years old accounting for about 10%. In countries with high prevalence of colorectal cancer, the age of prevalence is 60-70 years old, and those under 30 years old account for about 6%. In 2000, there were 700,000 new cases of colorectal cancer and 500,000 deaths in the world, and the incidence rate of colorectal cancer jumped to the second place in Shanghai in 2003, reaching 13.81% of malignant tumors. Therefore, early detection and early treatment of colorectal cancer are especially important to improve the survival rate of patients. Seventy percent of colorectal cancer occurs in the rectum, and 80% of rectal cancer occurs in the lower part of the rectum, i.e., the location that can be palpated by finger diagnosis, which is a favorable condition for early detection of rectal cancer. The early symptom of rectal cancer is blood in stool, so how to distinguish blood in stool from hemorrhoids? There are two types of patients: one is to panic and blindly seek medical treatment when they see blood in stool; the other is to delay medical treatment because of carelessness. Neither of these is desirable. For patients with blood in the stool can judge for themselves, the initial understanding of the nature of the disease, general blood in the stool bright red, no mucus, no other accompanying symptoms can basically be considered hemorrhoids blood in the stool. If the blood in the stool is purple in color and mucus is mixed with anorectal swelling, deformation of stool and weight loss, rectal tumor should be considered first. However, early tumors may only have purple-colored blood or mucus in the stool, so you should go to the hospital as soon as possible to find out the nature of the blood in the stool and the disease.