is the appendix part of the colon
About the appendix. The appendix is a pouch-like tube that is attached to the cecum, which is the first section of the large intestine or colon. The appendix averages 10 centimeters (about 4 inches) in length. It is considered part of the gastrointestinal (GI) tract. Generally thought to have no significant function in the body, the appendix may be a part of the lymphatic, exocrine, or endocrine systems. Appendix cancer occurs when healthy cells in the appendix change and grow out of control. These cells form a growth of tissue, called a tumor. A tumor can be cancerous or benign. A cancerous tumor is malignant, meaning it can grow and spread to other parts of the body.