Appendix cancer is a rare type of cancer that originates from the cells making up the appendix, a small finger-shaped pouch connected to the large intestine. While the exact function of the appendix is not fully understood, it is believed to play a role in the immune system.
Prevalence and Incidence
Appendix cancer is a notably rare malignancy, with its incidence often reported as affecting approximately 0.15 to 0.9 individuals per 100,000 people annually. Some estimates suggest it impacts around 1 to 2 people per million each year. This represents a very small fraction, less than 1%, of all gastrointestinal cancers diagnosed yearly in the United States.
Prevalence and incidence describe different aspects of disease occurrence. Incidence refers to the rate at which new cases of a disease appear in a population over a specific period, while prevalence indicates the total number of existing cases in a population at a given time.
Accurately tracking appendix cancer presents challenges due to its rarity and how it is often discovered. Many cases are diagnosed incidentally, found by chance during surgery for another condition like suspected appendicitis, or through unrelated imaging tests. This incidental discovery can lead to an underestimation of its true incidence in cancer registries. Studies indicate a slight increase in incidence rates over time, with some reports showing a significant rise, particularly among younger adults.
Types of Appendix Cancer
Appendix cancer is not a single disease but rather a group of distinct types, each arising from different cells within the appendix and exhibiting varied behaviors. Classifying these tumors accurately is important for understanding their nature.
Neuroendocrine tumors (NETs), also known as carcinoid tumors, are considered the most common type of appendix cancer, accounting for about half of all diagnosed cases. These tumors originate from hormone-producing cells and typically grow slowly. Another significant category is appendiceal adenocarcinoma, which begins in the glandular tissue lining the appendix.
Within adenocarcinomas, several subtypes exist, including mucinous adenocarcinoma, which produces a jelly-like substance called mucin. Goblet cell adenocarcinoma, sometimes called goblet cell carcinoid, is less common and possesses features of both adenocarcinomas and neuroendocrine tumors, often behaving more aggressively than NETs. Colonic-type adenocarcinoma, another subtype, is usually found near the base of the appendix and can mimic colon cancer. Signet-ring cell adenocarcinoma is a very rare and aggressive type.
Symptoms and Diagnosis
Appendix cancer often presents with non-specific or subtle symptoms, making early detection difficult. Many individuals experience no symptoms until the cancer has advanced or spread.
The most common way appendix cancer is discovered is during surgery for suspected appendicitis, as the tumor can obstruct the appendix and cause inflammation. Symptoms that might prompt investigation, though not exclusive to appendix cancer, include abdominal pain, bloating, an increase in waist size, and changes in bowel habits like diarrhea. Other possible signs include fluid buildup in the abdomen, nausea, vomiting, or feeling full quickly after eating.
Once suspicion arises, diagnostic methods typically involve imaging scans such as computed tomography (CT) and magnetic resonance imaging (MRI), which can visualize tumors and assess their extent. A definitive diagnosis usually requires a biopsy, where a small tissue sample is taken from the tumor and examined under a microscope by a pathologist.
Prognosis and Treatment Overview
The outlook for individuals with appendix cancer depends on several factors, including the specific type of cancer, how far it has spread at diagnosis (its stage), and the patient’s overall health. Early detection generally correlates with improved outcomes.
Treatment plans for appendix cancer are highly individualized due to the diversity of tumor types and stages. Surgery is the most common approach, aiming to remove the tumor and any affected surrounding tissue. This might involve removing only the appendix (appendectomy) or a portion of the colon (hemicolectomy), depending on the tumor’s size and spread.
Chemotherapy, either systemic (throughout the body) or regional (directly to the abdomen, such as Hyperthermic Intraperitoneal Chemotherapy or HIPEC), may be used in conjunction with surgery, especially if the cancer has spread. HIPEC involves heated chemotherapy solution delivered into the abdominal cavity during surgery to target remaining cancer cells. While radiation therapy is less commonly a primary treatment, it may be considered for specific areas of spread or symptom management.