The appendix is a small, finger-shaped organ of the digestive system that is located near where the large and small intestines come together. While it may be a source of healthy bacteria, the appendix is not a vital organ, so it is often removed if infection, inflammation, or disease occurs.
Cancer of the appendix is diagnosed in fewer than 1,500 Americans each year. A difficult cancer to detect, it is often discovered incidentally during surgery for appendicitis or during a CT scan for an unrelated condition. Because appendix cancer is so rare, there are no screening tests.
Treatments and outcomes depend on the cancer’s size, type, stage, and location. A tumor that is smaller than two centimeters and entirely contained within the appendix is more treatable. If the cancer is larger, or has spread to other areas of the body, it will require aggressive treatment.
Types of Appendix Cancer
Cancer of the appendix is classified by the type of cells within the tumor. The main types are:
The most common type of appendix cancer, carcinoid tumors account for approximately half of all diagnosed cases. They are a type of gastrointestinal neuroendocrine tumor (NET) usually found at the tip of the appendix. Because they are small and generally asymptomatic, these tumors are typically found after the appendix has been removed.
These tumors arise from the epithelial cells that line the inside of the appendix. Specific types of these tumors include:
Mucinous Tumors of the Appendix
Tumors that produce mucin can be either benign or cancerous.
Benign tumors, such as LAMNs (low grade appendiceal mucinous neoplasms), can spread and accumulate within the abdominal cavity, leading to pseudomyxoma peritonei (often referred to as PMP or “jelly belly”) or disseminated peritoneal adenomucinosis (DPAM). Although these tumors are considered benign, they can be fatal if left untreated.
Malignant tumors, also known as mucinous adenocarcinomas, can spread cancerous cells throughout the body or cause peritoneal carcinomatosis (another type of cancer).
Adenocarcinoid Tumors or Goblet Cell Carcinoids
These rarer tumors behave and are treated similarly to mucinous adenocarcinomas. They are generally more aggressive than carcinoid tumors.
Adenocarcinomas (also called Colonic-Type Adenocarcinomas)
About 10 percent of cancerous appendix tumors are found to be intestinal-type adenocarcinomas, which are usually found near the base of the appendix. These are generally treated in the same way as colorectal cancers.
If symptoms occur, they are similar to the symptoms of colorectal cancer (diarrhea, constipation, bleeding, or cramping).
Signet Ring Cell Carcinomas or Signet Ring Adenocarcinoma
A very rare and aggressive type of cancer. These tumors typically occur in the stomach, colon, or appendix and often cause appendicitis.
Symptoms of Appendix Cancer
Cancer of the appendix usually does not cause noticeable symptoms until it has reached an advanced stage and spread to other parts of the body. The primary symptom—bloating or an increase in the size of the abdomen—could be an indication of many other illnesses, so it’s important to make an appointment with a physician to have this evaluated. Other possible signs of appendix cancer include:
- Vague discomfort in the lower right abdomen
- Pelvic discomfort
- Acute or chronic abdominal pain
- Bowel obstruction
- Ovarian masses
- Shortness of breath
- Loss of appetite
- Indigestion or reflux
- Nausea or vomiting
- Flushing or redness in the face and neck
Risk Factors: What Causes Appendix Cancer?
In most cases of cancer, researchers haven’t yet identified the exact reason behind the abnormal cell division process. However, chances of developing cancer of the appendix may increase if you have the following risk factor:
- A personal history of smoking
Having this risk factor does not mean you will develop appendiceal cancer, and some people with appendiceal cancer do not have a history of smoking.