There are two main parts to the bowel, the small bowel and the large bowel. The food we eat ends up in the large bowel where water and some nutrients are absorbed leaving waste. This passes through the bowel before leaving the body. The most common type of bowel cancer affects the large bowel, which includes the colon and the back passage.

https://www.cancerresearchuk.org/about-cancer/bowel-cancer/about-bowel-cancer