The elderly group is relatively special. If a patient has chronic abdominal pain, diarrhoea, a feeling of urgency and mucopurulent stools, then lower gastrointestinal tumours are highly suspected. Clinically, it is important not to make an easy diagnosis of related diseases without colonoscopy in older people who have recently developed or changed symptoms in the lower gastrointestinal tract, so as not to miss the diagnosis of colorectal cancer.