Appendix Cancer

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 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 regions 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.

Every person is different, with different factors influencing their risk of being diagnosed with this cancer and their chance of recovery after a diagnosis. It is important to talk with your doctor about any questions you have about the general statistics provided below and what they may mean for you individually. The original sources for these statistics are provided at the bottom of this page.

How many people are diagnosed with appendix cancer?

Primary appendix cancer is cancer that starts in the appendix. Primary appendix cancer is very uncommon, affecting about 1 to 2 people out of every 1 million people. It is more common among people between 50 and 55 years of age. The number of people diagnosed with appendix cancer appears to have increased over the last 2 decades. This is especially true for malignant neuroendocrine tumors of the appendix diagnosed in younger people.

What is the survival rate for appendix cancer?

There are different types of statistics that can help doctors evaluate a person’s chance of recovery from appendix cancer. These are called survival statistics. A specific type of survival statistic is called the relative survival rate. It is often used to predict how having cancer may affect life expectancy. The relative survival rate looks at how likely people with appendix cancer are to survive for a certain amount of time after their initial diagnosis or start of treatment compared to the expected survival of similar people without this cancer.

Example: Here is an example to help explain what a relative survival rate means. Please note that this is only an example and not specific to this type of cancer. Let’s assume that the 5-year relative survival rate for a specific type of cancer is 90%. “Percent” means how many out of 100. Imagine there are 1,000 people without cancer, and based on their age and other characteristics, you expect 900 of the 1,000 to be alive in 5 years. Imagine that there are another 1,000 people similar in age and other characteristics as the first 1,000, but they all have the same specific type of cancer that has a 5-year survival rate of 90%. This means it is expected that 810 of the people with the specific cancer (90% of 900) will be alive in 5 years.

It is important to remember that statistics on the survival rates for people with appendix cancer are only an estimate. They cannot tell an individual person if cancer will or will not shorten their life. Instead, these statistics describe trends in groups of people previously diagnosed with the same disease, including specific stages of the disease.

For grade 1 or grade 2 gastrointestinal (GI) neuroendocrine tumors overall, a category that includes neuroendocrine tumor of the appendix, the 5-year relative survival is between 68% and 97%. Due to the rare nature of other types of appendix cancer, specific statistics are not available. Talk with your doctor about the factors related to your specific diagnosis.

The 5-year relative survival rates for appendix cancer vary based on several factors. These include the stage of disease at time of diagnosis, a person’s age and general health, and how well the treatment plan works. Another factor that can affect outcomes is the type of appendiceal tumor (see “Types of appendix tumors” in the Introduction).

Experts measure relative survival rate statistics for appendix cancer every 5 years. This means the estimate may not reflect the results of advancements in how appendix cancer is diagnosed or treated from the last 5 years. Talk with your doctor if you have any questions about this information. Learn more about understanding statistics.

Statistics adapted from the websites of the American Cancer Society, National Cancer Institute, and the National Organization for Rare Disorders. Additional reference are: Singh H. et al. Continued increasing incidence of malignant appendiceal tumors in Canada and the United States: A population-based study. Cancer. 2020;126(10):2206-2216. doi:10.1002/cncr.32793. (All sources accessed February 2023.)

Appendix: Cancer: Risk Factors

What are the risk factors for appendix cancer?

A risk factor is anything that increases a person’s chance of developing cancer. Although risk factors often influence the development of cancer, most do not directly cause cancer. Some people with several known risk factors never develop cancer, while others with no known risk factors do. Knowing your risk factors and talking about them with your doctor may help you make more informed lifestyle and health care choices.

The cause of appendix cancer is unknown, and no avoidable risk factors have been identified. The following factors may raise a person’s risk of developing appendix cancer:

• Age. The only consistent risk factor for various types of appendix cancer is increasing age. Appendix: cancer is rare in children.
• Sex. Neuroendocrine tumors of the appendix are more common in women.

What are the symptoms and signs of appendix cancer?

Symptoms are changes that you can feel in your body. Signs are changes in something measured, like taking your blood pressure or doing a lab test. Together, symptoms and signs can help describe a medical problem. Sometimes, people with appendix cancer do not have any of the symptoms and signs described below. Or, the cause of a symptom or sign may be a medical condition that is not cancer. People with appendix cancer may experience one or more of the following symptoms or signs:

• Appendicitis, which is inflammation of the appendix
• Ascites, which is fluid in the abdomen
• Bloating
• Pain in the abdomen or pelvis area
• Increased girth (size of the waistline), with or without a protrusion of the navel (bellybutton)
• Changes in bowel function
• Infertility, which is the medical inability to have a child,

If you are concerned about any changes you experience, please talk with your doctor. Your doctor will try to understand what is causing your symptom(s). They may do an exam and order tests to understand the cause of the problem, which is called a diagnosis.

If cancer is diagnosed, relieving symptoms remains an important part of cancer care and treatment. Managing symptoms may also be called “palliative and supportive care,” which is not the same as hospice care given at the end of life. This type of care focuses on managing symptoms and supporting people who face serious illnesses, such as cancer. You can receive palliative and supportive care at any time during cancer treatment. Learn more in this guide’s section on Coping With Treatment.

Be sure to talk with your health care team about the symptoms you experience, including any new symptoms or a change in symptoms.

Doctors use many tests to find, or diagnose, cancer. They also do tests to learn if cancer has spread to another part of the body from where it started. If the cancer has spread, it is called metastasis. Doctors may also do tests to learn which treatments could work best.

For most types of cancer, a biopsy is the only sure way for the doctor to know if an area of the body has cancer. In a biopsy, the doctor takes a small sample of tissue for testing in a laboratory. If a biopsy is not possible, the doctor may suggest other tests that will help make a diagnosis.

How appendix cancer is diagnosed

There are different tests used for diagnosing appendix cancer. Not all the tests described here will be used for every person. Your doctor may consider these factors when choosing a diagnostic test:

• The type of cancer suspected
• Your signs and symptoms
• Your age and general condition
• The results of earlier medical tests

In addition to a physical exam, the following tests may be used to diagnose appendix cancer:

• Biopsy. A biopsy is the only way to make a definite diagnosis, even if other tests can suggest that cancer is present. During a biopsy, a small amount of tissue is removed for examination under a microscope. A pathologist analyzes the sample(s). A pathologist is a doctor who specializes in interpreting laboratory tests and evaluating cells, tissues, and organs to diagnose disease.
  However, appendix cancer is often found unexpectedly during or after abdominal surgery for another reason. If cancer is suspected at the time of surgery, the doctor will remove a portion of the colon and surrounding tissue (called a margin) for examination. Often, a patient will have an appendectomy, which is the surgical removal of the appendix. This is usually done for what is first thought to be appendicitis, and the cancer is diagnosed after the pathologist has looked at the tissue under the microscope. In that case, another surgery may be recommended to remove another margin of tissue around the area where the tumor began, depending on the type of appendix cancer (such as a neuroendocrine or adenocarcinoma tumor) and the size of the tumor (if it is a neuroendocrine tumor). Appendix: Cancer may also be discovered by accident when a CT scan is done for another reason.
• Computed tomography (CT or CAT) scan. A CT scan takes pictures of the inside of the body using x-rays taken from different angles. A computer combines these pictures into a detailed, 3-dimensional (3D) image that shows any abnormalities or tumors. A CT scan can be used to measure the tumor’s size. Sometimes, a special dye called a contrast medium is given before the scan to provide better detail on the image. This dye can be injected into a patient’s vein or given as a pill or liquid to swallow.
• Magnetic resonance imaging (MRI). An MRI produces detailed images of the inside of the body using magnetic fields, not x-rays. An MRI can be used to measure the tumor’s size. A special dye called a contrast medium is given before the scan to create a clearer picture. This dye can be injected into a patient’s vein or given as a pill to swallow.
• Ultrasound. An ultrasound creates a picture of the internal organs using sound waves.
• Biomarker testing of the tumor. Your doctor may recommend running laboratory tests on a tumor to identify specific genes, proteins, and other factors unique to the tumor. This may also be called molecular testing of the tumor. Biomarker testing can also be done through a blood test called a liquid biopsy. The results of these tests can help you determine your treatment options.
• Radionuclide scanning (68Ga-DOTATATE PET scan or OctreoScan). These tests are used for neuroendocrine tumors and not other types of appendix cancers. A small amount of a radioactive, hormone-like substance that is attracted to a neuroendocrine tumor is injected into a vein. The amount of radiation in the substance is too low to be harmful. A special camera is then used to show where the radioactive substance accumulates. This procedure is useful in detecting the spread of a neuroendocrine tumor.

After the diagnostic tests are done, your doctor will review the results with you. If the diagnosis is appendix cancer, these results also help the doctor describe the cancer and determine where the cancer is in the body. This is called staging.