Appendix Cancer: Introduction

Approved by the Cancer.Net Editorial Board, 12/2023

ON THIS PAGE: You will find some basic information about appendix cancer and the parts of the body it may affect. This is the first page of Cancer.Net’s Guide to Appendix Cancer. Use the menu to see other pages. Think of that menu as a roadmap to this entire guide.

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. Another name for appendix cancer is appendiceal cancer. A benign tumor means the tumor can grow but will not spread.

Types of appendix tumors

There are different types of tumors that can start in the appendix:

  • Neuroendocrine tumor. A neuroendocrine tumor starts in the hormone-producing cells that are normally present in small amounts in almost every organ in the body. A neuroendocrine tumor usually starts in either the GI tract (when it is often called a carcinoid tumor), pancreas, or a lung, but it also may occur in the testicles or ovaries. An appendix neuroendocrine tumor most often occurs at the tip of the appendix. About half of all appendix tumors are neuroendocrine tumors. Appendix cancer usually causes no symptoms until it has spread to other organs and often goes unnoticed until it is found during an examination or procedure performed for another reason. An appendix neuroendocrine tumor that remains confined to the area where it started has a high chance of successful treatment with surgery. Learn more about neuroendocrine tumors (NETs) of the GI tract.

  • Appendiceal mucoceles. Mucoceles are swellings or sacs from swelling of the appendix wall, typically filled with mucus. There is a range of benign to malignant conditions that can occur in the appendix to form a mucocele. Two of these conditions are mucinous cystadenomas and mucinous cystadenocarcinomas. Mucinous cystadenomas are benign and do not spread, and they are similar to adenomatous polyps that can develop in the colon. When contained in the appendix, they can be completely removed with surgery. However, if the appendix ruptures, the cells may spread in the body cavity and continue to secrete a jelly-like substance called mucin into the abdomen. The buildup of mucin can lead to abdominal pain, bloating, and changes in bowel function, including bowel obstruction (blockage). Mucinous cystadenocarcinomas can have similar effects with mucin in the abdomen, but they are malignant, meaning they can spread to other parts of the body.

  • Colonic-type adenocarcinoma. Colonic-type adenocarcinoma accounts for about 10% of appendix tumors and usually occurs at the base of the appendix. It looks and behaves like the most common type of colorectal cancer. It often goes unnoticed, and a diagnosis is frequently made during or after surgery for appendicitis. Appendicitis is inflammation of the appendix that can cause abdominal pain or swelling, loss of appetite, nausea, vomiting, constipation or diarrhea, inability to pass gas, or a low fever that begins after other symptoms.

  • Signet-ring cell adenocarcinoma. Signet-ring cell adenocarcinoma is rare. It is considered to be more aggressive and more difficult to treat than other types of adenocarcinomas. It is called signet-ring cell adenocarcinoma because, under the microscope, the cell looks like it has a signet ring inside it. This type of appendix cancer is treated similarly to colon cancer.

  • Goblet cell carcinomas/adenoneuroendocrine tumors. Goblet cell carcinomas have features of both adenocarcinomas and neuroendocrine tumors (both described above). They are more aggressive than neuroendocrine tumors, and treatment is often similar to treatment for adenocarcinoma.

  • Paraganglioma. This is a rare tumor that develops from cells of the paraganglia, a collection of cells that come from nerve tissue that remain in small deposits after fetal (pre-birth) development. Paraganglia is often found near the adrenal glands and some blood vessels and nerves, including in the head and neck region of the body. This type of tumor is usually considered benign and is often successfully treated with the complete surgical removal of the tumor. Learn more about paraganglioma.

Looking for More of an Introduction?

If you would like more of an introduction, explore these related items. Please note that these links will take you to other sections on Cancer.Net:

The next section in this guide is Statistics. It helps explain how many people are diagnosed with appendix cancer and general survival rates. Use the menu to choose a different section to read in this guide.