Appendix Cancer

Appendix cancer is one of the rarest GI cancers, accounting for less than 1% of gastrointestinal cancers globally. Fewer than 2 people per million are diagnosed each year, though incidence has been rising steadily and rates in the US have more than tripled over roughly two decades. This rising trend has been confirmed in the United States, Canada, and the United Kingdom, with neuroendocrine tumors showing the steepest increase, especially in patients under 50. It's expected that there will be a 25–50% global increase of appendix cancer by 2030.

Rates of appendiceal adenocarcinoma more than tripled among people born between 1976–1984, and quadrupled among those born between 1981–1989.

Appendix cancer is often caught at later stages, once it has spread to nearby organs, making it aggressive and difficult to treat. Appendix cancer is frequently misdiagnosed as appendicitis, IBS, or ovarian pathology, or it's incidentally found.

It is considered an "orphaned disease," meaning there are currently no FDA-approved drugs specifically for its treatment. In 2025, the National Comprehensive Cancer Network (NCCN) established the first-ever provider guidelines for treating appendiceal neoplasms and cancers, a significant step forward.

What is appendix cancer?

The appendix is located in the lower right area of the abdomen. It looks like a finger and sticks out from the colon. Its purpose is still being researched, however it may play a role in the immune system.

Appendix cancer forms in the cells lining the appendix and grows outward as it spreads. There are several types of appendix cancer, and treatment plans are customized based on what type of cells have become cancerous and how they’re behaving.  

Pseudomyxoma peritonei

A syndrome known as pseudomyxoma peritonei (PMP) often accompanies appendix cancer. A signature of PMP is tumor cells that produce mucin (a jelly-like substance) in the abdomen. The tumor cells almost always start in the appendix but can then spread to other sites, like the stomach or ovary. PMP can increase your abdominal size, create pain or pressure, or give you an “I ate too much” feeling. Sometimes these symptoms are what lead to the discovery of appendix cancer.  

Types of appendix cancer

The histologic grade (also called “grade”) of appendix cancer is very important. This measures how aggressive the cancer is. Grades fall within low-grade (slow-growing cancers that are typically non-invasive and do not respond well to chemotherapy) and high-grade (fast-growing cancers that are invasive and may be more responsive to chemotherapy). 

In addition to the grade, these tumors may also be described by their “differentiation,” which describes normal or abnormal cells and whether or not they contain mucin, a jelly-like substance.

There are several types of appendix cancer:

Mucinous appendiceal neoplasms (LAMN/HAMN)

These tumors are not necessarily cancerous, but they pose a cancer risk if their mucin carries tumor cells and it leaks outside the appendix. A LAMN that has already ruptured and spread mucin to the peritoneum is considered a form of low-grade malignancy (low-grade PMP).

Appendiceal adenocarcinoma

This begins in the lining of the appendix. Tumors usually produce mucin. Subsets include:

Signet ring cell carcinoma (SRCC)

This is rare and tends to be more aggressive, it may spread to lymph nodes and/or the peritoneum inside of the abdomen.

Goblet cell adenocarcinoma (GCA)

GCA is an adenocarcinoma with mucin-secreting cells and a minor neuroendocrine component. It is more aggressive than appendiceal NETs but less aggressive than signet ring cell carcinoma or poorly differentiated adenocarcinoma. You may see it referred to as 'goblet cell carcinoid' in older records.

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Carcinoid, also known as neuroendocrine tumors (NET)

This makes up about half of all appendix cancers. Neuroendocrine tumors can appear in multiple places throughout the GI tract, including the appendix. These cancers need to be treated differently than adenocarcinomas. 

Read more about neuroendocrine cancer.

Staging appendix cancer

If you have appendix cancer, your treatment plan will be formed based on the type of cancer and your stage. Staging appendix cancer is complex because there are many factors and variables.

Appendiceal adenocarcinomas (SRCC and GCA) are staged on a scale from 0-4 (researchers use roman numerals 0-IV) based on the TNM staging system. In general:

• Stage 0 (carcinoma in situ): Cancer is in one spot and has not spread anywhere else.
• Stage 1: Cancer is confined to the inner layers of the appendix.
• Stage 2: Cancer has grown into connective or fatty tissue, to the outer layers of the appendix, and/or into the colon or rectum, but not to lymph nodes or distant organs.
• Stage 3: Cancer has grown into lymph nodes
• Stage 4 (also called “metastatic”): Cancer has spread to the abdomen and possibly other organs like the lungs; it may or may not be in lymph nodes.

What causes appendix cancer?

Risk factors put you at a higher risk of getting cancer. Some risk factors can be controlled with lifestyle changes, and others cannot. Older age, smoking, and obesity increase your risk of many cancers.

Just because you have a risk factor, that doesn’t mean you will get cancer. 

Most of the risk factors for appendix cancer are unknown; however these factors have been linked to cases: 

• Some studies suggest chronic use of antacids 
• Certain genetic diseases: familial adenomatous polyposis (FAP), Lynch syndrome, and multiple endocrine neoplasia type 1 (MEN1) syndrome 
• Personal history of GI tumors
• Family history of appendix cancer
• Low stomach acid (hypochlorhydria) 

Preventing appendix cancer

There are not any known ways to prevent appendix cancer. Researchers are still learning about what causes it.

As with every cancer, there are steps you can take to adopt a healthy lifestyle and reduce your overall cancer risk, such as maintaining a healthy weight, not smoking, and limiting or eliminating alcohol. 
Learn more about cancer prevention from the American Institute for Cancer Research.

What are some appendix cancer statistics? 

Appendix cancer is a rare disease.

According to global epidemiological data published in Healthcare:

• Appendix cancers account for less than 1% of gastrointestinal cancers globally, but incidence is increasing worldwide and some models predict a 25–50% increase in global incidence by 2030.
• A rising trend in incidence has been confirmed in the United States, Canada, and the United Kingdom, with NET tumors showing the steepest increases in patients under 50.

According to Annals of Internal Medicine (2025):

• Rates of appendiceal adenocarcinoma more than tripled among people born between 1976–1984, and quadrupled among those born between 1981–1989, compared to the 1945 birth cohort.

According to other published clinical literature:

• Most appendix cancers are diagnosed in people aged 55–65.
• Men and women are at roughly equal risk for most subtypes, with the exception of neuroendocrine tumors, which are more common in women.
• The vast majority of appendix cancers are discovered incidentally, often when a surgeon removes an appendix for suspected appendicitis and a pathologist examines the tissue. Fewer than 2% of all appendectomies reveal a tumor.

What are my odds of surviving it?

Because there are so few cases, survival statistics may not be accurate. However, the latest data shows:

• 60-90% of patients with NET or other low-grade tumors are alive five years after diagnosis
• Early-stage low-grade mucinous neoplasms found incidentally have a 5-year survival of up to 97%
• Advanced mucinous adenocarcinoma with peritoneal spread has a 5-year survival of around 30% even with aggressive treatment.

What types of tests should I expect to undergo?

Appendix cancer is challenging to find in its earliest stages, because it often has few symptoms. It’s often found when a patient is being seen for appendicitis or undergoing surgery for a different problem. 

Doctors may use these tests to find and diagnose appendix cancer:

• Physical exam
• Imaging (CT, MRI, ultrasound, PET scan)
• Blood tests
• Urine tests
• Diagnostic Laparoscopy
• Scopes (like a colonoscopy)
• Biopsy

Ask your doctor about these additional tests—ideally before you begin treatment.

• Biomarker testing
• Genetic testing

I’m facing a diagnosis: What are my next steps?

If you’re facing a diagnosis, the GI Cancers Alliance is here for you. 

If you’re newly diagnosed, work with your doctor to create a treatment plan. 

It’s important to find an expert who specializes in appendiceal cancer. Ask your doctor about you peritoneal cancer index (PCI), which is the scoring system surgeons use to measure the extent of peritoneal spread and determine whether complete cytoreduction is achievable.

The top experts running clinical trials are looking into the molecular differences between colon cancer and appendix cancer. Although closely related, these two cancer types have shown different responses to treatment in clinical trials.

Surgical Centers of Excellence are often good places to start when making a treatment plan, as surgery (and possibly HIPEC) is often the first step in treating appendix cancer. You will need a multi-disciplinary team with oncologists, surgeons, and pathologists.

Most appendix cancer treatment plans include:

• Surgery (usually appendectomy, hemicolectomy, or cytoreductive (debulking))
• Chemotherapy (HIPEC may be recommended)
• Clinical trials (that may involve targeted therapy or immunotherapy)
• Radiation (less commonly used)

Chemotherapy?

It's important to know that chemotherapy for patients with low-grade mucinous appendiceal adenocarcinoma have shown a poor response to systemic treatment and it has not impacted overall survival. A patient with a low-grade tumor who is offered or pushed toward systemic chemotherapy before CRS/HIPEC needs to know this. Surgery is the primary treatment for low-grade disease, not chemotherapy.

What about Appendiceal NET?

The vast majority of appendiceal NETs (which make up over 50% of all appendix tumors) are small, localized, and cured by appendectomy alone.

We strongly encourage you to get a second opinion from another trusted doctor so you feel confident moving forward.