Most colon and rectal cancers are located in the sigmoid colon and rectum. However, data in recent years have shown an increase in the incidence of proximal segment cancer. Even when the presence of tumor has been detected, there are still some patients who remain clinically asymptomatic. Blood loss and anemia due to tumor bleeding are common clinical manifestations. Many patients experience changes in bowel habits, with thin or unformed stools and blood in the stool; in the right hemocolon, a bulging mass is often formed; in the left hemocolon, constipation often occurs because the stool is often blocked by the annular tumor; patients may have abdominal distention. Tumors of the rectum and sigmoid colon often cause urgency. In addition, other symptoms may include fever, malaise, weight loss and abdominal pain. Some advanced patients present with obstruction or perforation complications. Modern imaging techniques allow for nondestructive detection and clinical staging. Conventional barium meal for larger tumors, air contrast radiology for small progressive tumor lesions, CT and transrectal ultrasonography can be used to detect the depth of tumor infiltration and the presence of local or distant lymph node metastases. Endoscopy is currently the most used. Colonoscopy allows detection of the entire mucosal surface of the large intestine and biopsy sampling of the lesions seen. The main methods of therapeutic endoscopy are trap polypectomy and endoscopic mucosal resection. The former is often used for prominent tumors, while the latter is chosen for superficial, some augmented lesions.