Appendix cancer types are categorized based on the type of cells involved and what the cells look like under a microscope. The cell types are named for their behaviors, such as the likelihood of spreading to other parts of the body, the rate of growth and ability to be removed surgically.
The two main types of appendix cancer are called neuroendocrine tumors and carcinomas:
Neuroendocrine (carcinoid) tumors (NET) are the most common appendix cancers, making up about half of those diagnosed. They are most often found in women in their 40s. These tumors begin in the hormone-producing cells and are typically found after the appendix has been removed. Most carcinoid tumors are small and difficult to diagnose because they are not visible on routine imaging studies. Surgery is often the first-line treatment.
Carcinomas begin in the tissue that lines the appendix. Carcinomas of the appendix include:
- Mucinous adenocarcinoma: The second most common type of appendix cancer, mucinous adenocarcinomas begin in the appendix and produce mucin, a jelly-like substance that tends to spread cancerous cells to other parts of the body. These tumors are often discovered after they have spread (metastasized) to the peritoneum (the lining of the abdominal cavity).
- Goblet cell carcinoids (also called adenocarcinoid tumors): These are less common tumors, which, despite the name, are not carcinoid tumors. Goblet cell carcinoids behave and are treated similarly to mucinous adenocarcinoma. They are often more aggressive than carcinoid tumors and typically develop in patients over the age of 50.
- Intestinal-type adenocarcinoma (also called colonic-type adenocarcinoma):These tumors account for about 10 percent of appendix tumors and are usually found near the base of the appendix. When these tumors cause symptoms, they often mimic the symptoms of colorectal cancer.
- Signet-ring cell adenocarcinoma: A very rare but aggressive type of appendix cancer, this type of tumor typically occurs in the stomach or colon. When it develops in the appendix, it often causes appendicitis. It is called signet-ring cell adenocarcinoma because, under the microscope, the cell looks like it has a signet ring inside it.
Next topic: What are the stages of appendix cancer?
