The intestines are part of the digestive system. There are two parts of the intestine: the small intestine and the large intestine. The large intestine is made up of the colon, the rectum, and the anus.
When food is ingested, it goes through the esophagus and into the stomach, where digestion begins. From here, it goes into the small intestine, where its essential nutrients are absorbed by the body. Food then goes into the colon, where water is absorbed. The remaining waste products (feces) go into the rectum, where they remain until they exit the body through the anus.
The rectum is the part of the intestine that connects the colon and the anus; it is 15 cm in size. To better establish where the tumor is located, the rectum is divided into three parts: upper (joining up with the sigmoid colon), middle, and lower (connecting with the anus).