Appendix cancer is a rare type of cancer that grows in the appendix. There are several different types of appendix cancer, and a person often experiences no symptoms in the early stages.

The appendix is a tubular, finger-like sac around 4 inches in length that connects to the first part of the colon. Scientists do not fully understand the exact purpose of this organ. People can live normal and healthy lives without their appendix.

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Appendix cancer, also known as appendiceal cancer, is extremely rare. Experts estimate that this type of cancer affects around 2 to 9 people per 1 million. Some studies suggest that appendix cancer may be on the rise, however.

A recent retrospective study estimated that it increased from around 6 people per 1 million in 2000 to as many as 10 people per 1 million in 2009.

In this article, we discuss the types, symptoms, causes, and risk factors of appendix cancer. We also cover diagnosis, treatment, and survival rates for this disease.

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Types

Man with appendix pain possibly caused by appendix cancer
Appendicitis may be the first sign of appendix cancer.

Appendix cancer includes several types of tumor cells that may affect various parts of the appendix.

Some appendix tumors are benign, meaning they do not invade and spread. Other tumors are malignant, and thus cancerous, which means they invade and can spread to or from other organs.

An appendix tumor may be one of the following types:

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  • Neuroendocrine tumor. Also known as a carcinoid tumor, this type usually starts in the tip of the appendix and accounts for more than half of appendiceal malignancies.
  • Mucinous cystadenoma. This is a benign tumor that starts in the mucoceles, which are mucus-filled areas of edema or sacs in the appendix wall. A mucinous cystadenoma is benign and does not spread to other organs when it is in an intact appendix. It is also known as a low-grade mucinous neoplasm.
  • Mucinous cystadenocarcinoma. This type of tumor also starts in the mucoceles, but it is malignant and can spread elsewhere. It accounts for about 20 percent of all cases of appendix cancer.
  • Colonic-type adenocarcinoma. About 10 percent of all appendix tumors are adenocarcinomas, and they usually start at the base of the appendix when originating in this organ. They can spread to other organs and areas of the body.
  • Goblet cell carcinoma. Also known as an adenoneuroendocrine tumor, this type of tumor has similar characteristics to both a neuroendocrine tumor and an adenocarcinoma. A goblet cell carcinoma may spread to other organs and tends to be more aggressive than a neuroendocrine tumor.
  • Signet-ring cell adenocarcinoma. A rare and difficult-to-treat malignant tumor, a signet-ring cell adenocarcinoma is faster growing and more difficult to remove than other adenocarcinomas.
  • Paraganglioma. This type of tumor is usually benign. However, medical literature has reported one rare case of a malignant paraganglioma in the appendix.

Symptoms

Appendix cancer often causes no symptoms in the early stages. Doctors often only first diagnose people with this condition in the later stages when it begins to cause symptoms or spreads to other organs. Doctors may also find it when evaluating or treating a patient for a different condition.

The signs and symptoms of appendix cancer often depend on the effects of the tumor:

Pseudomyxoma peritonei

Some types of appendix tumors can cause pseudomyxoma peritonei or PMP, which occurs when the appendix ruptures and the tumor cells leak into the abdominal cavity. The tumor cells secrete a protein gel called mucin that can build up in the abdominal cavity and continue to spread.

PMP may involve cancer cells that leak into the abdominal cavity. Without treatment, its buildup can lead to problems with the digestive system and intestinal blockages. Mucinous cystadenomas and mucinous cystadenocarcinomas of the appendix may cause PMP.

PMP symptoms include:

  • abdominal pain that may come and go
  • swollen or enlarged abdomen
  • loss of appetite
  • feeling full after eating only small amounts of food
  • nausea or vomiting
  • constipation or diarrhea
  • inguinal hernia, containing mucus and more common in males

Appendicitis

Appendicitis, which is inflammation of the appendix, may be the first sign of appendix cancer. This is mostly because some appendix tumors can block the appendix, leading to the bacteria that are normally in the intestines becoming trapped and overgrowing inside the appendix.

The most common treatment for appendicitis is emergency surgery to remove the appendix. Once the surgeon removes the appendix, a biopsy of the tissue may reveal that the person has appendix cancer.

Appendicitis symptoms typically include severe pain in the abdomen that:

  • occurs between the bellybutton and lower right abdomen
  • gets worse with movement or deep breaths
  • comes on suddenly and gets worse quickly

Appendicitis may also cause:

  • abdominal swelling
  • nausea or vomiting
  • constipation or diarrhea

Not all types of appendix cancer will cause appendicitis. For instance, the majority of neuroendocrine tumors form in the appendix tip, so they are unlikely to cause a blockage that could lead to appendicitis.

It is also important to note that many people who get appendicitis do not have appendix cancer. Other factors, such as trauma to the abdomen and inflammatory bowel disease can cause appendicitis. Many cases of appendicitis have no known cause.

Other signs of appendix cancer

In some cases, people with appendix cancer may discover a hard mass in the abdomen or pelvic area. They may also have abdominal pain or swelling. In females, a mass from appendix cancer may be mistaken for ovarian cancer.

If the appendix cancer is malignant, the cancer cells may grow on the surface of other abdominal organs and the lining of the abdominal cavity. This progression is known as peritoneal carcinomatosis. If left untreated, a person may lose function of their intestines or have an intestinal blockage.

Malignant appendix cancer most commonly grows on the surface of the:

  • liver
  • spleen
  • ovaries
  • uterus
  • lining of the abdominal cavity or peritoneum

Usually, cancers of the appendix do not spread to organs outside of the abdominal cavity with the exception of signet-ring cell adenocarcinomas.

Causes and risk factors

Experts do not yet know exactly what causes appendix cancer. They have not discovered any links between appendix cancer and genetic or environmental causes.

Doctors mostly believe that appendix cancer affects males and females equally. Because it is rare in children, being an adult is the only known risk factor. Most people are between 40 and 59 years of age when a doctor diagnoses them with appendix cancer.

Diagnosis

Doctors diagnose many appendix cancers after a person has had appendicitis surgery or when the tumor spreads to other organs, causing symptoms.

It is difficult for doctors to specifically identify appendix cancer on imaging tests such as ultrasound, MRI, or CT scans. Likewise, blood tests are not a reliable indicator of appendix cancer.

Often, a doctor can diagnose a person with appendix cancer after obtaining a biopsy of the tumor.

Treatment

doctor speaking to patient
Treating appendix cancer may include surgery and chemotherapy.

A person’s healthcare team will determine the best treatment for appendix cancer based on several factors, including:

  • the type of tumor
  • if and where cancer has spread
  • any other health issues affecting the person

If cancer has not spread beyond the appendix, a person may only need surgery. If it has spread to other organs, the surgeon may be able to remove the affected organs to eliminate all cancer. This may include part of the intestines, ovaries, or peritoneum.

The American Association of Endocrine Surgeons state that most people benefit from surgery that removes the appendix and the right half of the colon, especially if the tumor is larger than 2 centimeters (cm). This procedure is known as a right hemicolectomy.

Some people may also undergo chemotherapy after surgery to help eliminate the cancer.

A procedure known as heated intraperitoneal chemotherapy, also called HIPEC, may be effective against appendix cancer that has spread into the abdominal cavity.

With HIPEC, the surgeon fills the abdomen with a heated chemotherapy solution and allows it to work for around 1.5 hours. This technique may eliminate cancer cells that the doctors cannot see. The surgeon will perform HIPEC after removing the appendix and any visible tumor cells.

HIPEC is new and may have a long recovery time, ranging from 8 weeks to several months. The Appendix Cancer and Pseudomyxoma Peritonei Research Foundation say people with appendix cancer and PMP should find surgeons with experience in appendix cancer surgery and HIPEC for the best outcome.

Survival rates

The survival rate for appendix cancer varies depending on the type of tumor, whether it has spread, and where it is.

Doctors use 5-year survival rates to provide a predictive indication of how many people will live for at least 5 years after diagnosis of their cancer. However, it is vital to note these figures are only estimates and everyone’s outlook will be different.

According to the American Society for Clinical Oncology, the 5-year survival rate for neuroendocrine tumors of the appendix is:

  • Nearly 100 percent if the tumor is smaller than 3 cm and has not spread.
  • Around 78 percent if the tumor is smaller than 3 cm and has spread to regional lymph nodes.
  • Around 78 percent if the tumor is larger than 3 cm, regardless of whether it has spread to other parts of the body.
  • Approximately 32 percent if the cancer has spread to other parts of the body.

The National Center for Advancing Translational Sciences states that for goblet cell carcinoma, generally, 76 percent of people will live for 5 years or longer following diagnosis.

Specific statistics are not available for other types of appendix cancer.

Takeaway

Appendix cancer is extremely rare, and it causes no symptoms in many people in the early stages. Doctors often only diagnose appendix cancer in the later stages when it starts spreading to other organs. Otherwise, it may be diagnosed incidentally while treating appendicitis or evaluating a different abdominal condition.

Because appendix cancer is so rare, many facts about it remain a mystery. People who have this type of cancer may benefit from online support groups where they can connect with others who are going through some of the same challenges and treatments.

Appendix cancer is treatable, and many people have good outcomes with the help of professional cancer care. A doctor can advise a person about their treatment options and health outlook.