About Appendix Cancer

About Appendix Cancer

Understanding a rare cancer

Appendix cancer is a rare form of cancer that begins in the appendix. Most people aren't aware of their appendix until there's a problem. Learning about this disease can help patients and families make informed decisions about treatment and care.

In this disease, abnormal cells grow uncontrollably inside the appendix. These cells sometimes form tumors, and they can also produce a jelly-like substance called mucin. If the tumor breaks through the wall of the appendix, mucin and cancer cells can spread into the abdominal cavity (belly).

There are several types of appendix cancer that generally fall into two grades:

  • Low-grade - tumors grow slowly and may be easier to manage
  • High-grade - tumors grow faster and may require more aggressive treatment

Because appendix cancer is so rare, it's often discovered by accident, such as during:

  • Surgery for appendicitis
  • A routine scan
  • Investigations of other abdominal symptoms

1. Low-Grade Mucinous Neoplasm (LAMN)

What it is:

  • A slow-growing appendix tumor that produces mucin, this jelly-like fluid can accumulate in the abdomen.
  • Often confined to the appendix or abdominal cavity; rarely spreads outside the abdomen (not to lymph nodes or through the blood stream to other organs).
  • May cause pseudomyxoma peritonei (PMP) if mucin leaks into the abdominal cavity.

2. High-Grade Mucinous Adenocarcinoma (HAMN)

What it is:

  • A faster-growing, more aggressive tumor that also produces mucin.
  • Can spread more widely in the abdomen and occasionally beyond.
  • Similar to LAMN but may progress more quickly.

3. Goblet Cell Adenocarcinoma

What it is:

  • A rare tumor with features of both adenocarcinoma and neuroendocrine tumors.
  • Usually more aggressive than typical neuroendocrine tumors.

4. Neuroendocrine Tumor (Carcinoid)

What it is:

  • Slow-growing tumor from hormone-producing cells of the appendix.
  • Can secrete hormones leading to carcinoid syndrome if it spreads to the liver.

5. Colonic-type Non-Mucinous Adenocarcinoma

What it is:

  • Resembles typical colon adenocarcinoma and does not produce mucin.
  • Tends to grow and spread more aggressively than mucinous tumors.

6. Signet Ring Cell Adenocarcinoma

What it is:

  • Rare, aggressive tumor where cells look like signet rings under the microscope.
  • Often spreads early and behaves more aggressively than other appendix cancers.

Pseudomyxoma Peritonei (PMP):

  • Pseudomyxoma Peritonei, or PMP, is a rare condition that occurs when certain appendix tumors (typically mucinous tumors) produce a thick, jelly-like fluid called mucin, which accumulates in the abdominal cavity.
  • PMP is not a separate type of cancer; it is a complication of mucin-producing appendix tumors.

How it develops:

  • Tumor cells in the appendix secrete mucin.
  • If the tumor ruptures or grows through the appendix wall, mucin and tumor cells can spread throughout the peritoneal cavity, coating the abdominal organs.
  • Unlike many cancers, PMP usually spreads along the surface of the abdominal cavity, rather than through the bloodstream or lymph nodes.

Symptoms:

PMP develops slowly, and early stages may have no symptoms. As mucin builds up, patients may experience:

  • Abdominal swelling or bloating
  • Abdominal or pelvic discomfort
  • Can be confused for appendicitis, ovarian cysts or tumors
  • Changes in bowel habits (constipation or obstruction)
  • Nausea or vomiting if the intestines are compressed
  • Hernias, especially in men
  • Reduced appetite or early feeling of fullness when eating

Diagnosis:

  • Imaging studies like MRIs and CT scans can detect mucin accumulation.
  • Surgery may be required for definitive diagnosis and treatment, often revealing widespread mucin deposits.

Treatment:

  • The standard treatment is cytoreductive surgery (CRS) to remove visible tumor and mucin, often followed by hyperthermic intraperitoneal chemotherapy (HIPEC) to target remaining cancer cells.
  • Complete removal of mucin and tumor deposits is associated with better long-term outcomes.

Prognosis:

Prognosis depends on tumor grade, completeness of surgery, and spread.

CRS + HIPEC is a specialized treatment for appendix cancer or pseudomyxoma peritonei (PMP) that has spread in the abdomen.

How it works:

  • Cytoreductive Surgery (CRS): is a long, complex operation where the surgeon carefully removes all visible cancer from the lining of the abdomen and, if needed, affected organs.
  • Hyperthermic Intraperitoneal Chemotherapy (HIPEC):
    • Hyperthermic = heated
    • Intraperitoneal = inside the peritoneal cavity (the space in your abdomen that holds your stomach, intestines, liver, and other organs)
    • Chemotherapy = cancer-fighting drugs
    • HIPEC circulates heated chemotherapy inside the abdomen to kill remaining cancer cells after CRS.

Why it's used:

  • Targets tumors within the abdomen.
  • Together, CRS and HIPEC aim to remove as much cancer as possible and lower the chance of it coming back in the abdomen.

How long is the CRS/HIPEC Surgery?

CRS/HIPEC is one of the longest and most complex surgeries in cancer care, and the time and extent depend on how far the cancer has spread.

Typical length:

  • Surgery can last 8–14 hours (sometimes shorter, sometimes longer).
  • The first part (CRS) — removing visible cancer — takes the most time.
  • The second part (HIPEC) — circulating heated chemotherapy in the abdomen — usually lasts 60–90 minutes.

What Organs might be removed?

This depends on where the cancer has spread. The goal is to take out all visible disease while preserving as much healthy tissue as possible. Organs or parts of organs that may be removed include:

  • Appendix
  • Parts of the colon or rectum
  • Small intestine (portions only — complete removal is rare)
  • Gallbladder
  • Ovaries and uterus (in women)
  • Spleen
  • Portions of the stomach
  • Portions of the peritoneum (the lining of the abdomen)
  • Omentum (a fatty layer covering abdominal organs)
  • Occasionally parts of the bladder, pancreas, kidney, liver or diaphragm if cancer is present there.

Every patient's surgery is unique — some may only need a few areas removed, while others may require a much more extensive operation.

Surgeons also differ in their approach. Some may be more conservative, while others take a more aggressive stance on which organs to remove. Additionally, some surgeons will not operate on advanced cases while others will.

Before surgery, your surgeon will review your scans and explain which areas are most likely to be affected. They may also talk with you about the possible need for an ostomy. An ostomy is a surgically created opening in the abdomen that allows waste (such as stool or urine) to leave the body if the normal pathway is blocked or removed. The waste is collected in a small pouch worn outside the body and may be temporary or permanent.

This is an important time to have an open conversation and agree together on the approach that feels right for you.

Recovery

Recovery after CRS/HIPEC can take time, and it's different for everyone. Most people stay in the hospital for about 1–2 weeks, if there are any complications potentially longer. It may take two months and potentially longer to get back to normal daily activities.

Many patients feel tired for several months after surgery. Depending on which organs were affected, it can also take effort to regain weight and figure out which foods work best for you.

Because recovery can be challenging, it helps to be as healthy as possible before surgery. Eating a balanced diet, keeping your weight stable, and working on strength and stamina can make recovery easier.

Additional Tips for CRS/HIPEC Recovery

  • Wound care: Follow your surgical team's instructions carefully to prevent infection. Watch for redness, swelling, or fever.
  • Nutrition support: Small, frequent meals may be easier to tolerate. Meeting with a dietitian can help with weight gain, protein needs, and digestion.
  • Hydration: Staying hydrated helps with healing, bowel function, and energy.
  • Pain management: Take pain medications as prescribed, and let your team know if pain is interfering with sleep, eating, or movement.
  • Physical activity: Gentle walking can help improve circulation, prevent blood clots, and rebuild strength. Gradually increase activity as advised. Avoid heavy lifting or straining to lower the risk of getting a hernia.
  • Fatigue management: Plan rest periods throughout the day and listen to your body.
  • Emotional health: Recovery can feel overwhelming. Connecting with a support group or therapist may help with stress, anxiety, or mood changes.
  • Follow-up care: Keep all follow-up appointments for lab tests and scans so your care team can monitor healing and watch for recurrence.
  • Support system: Ask family, friends, or community resources for help with meals, transportation, or daily tasks while you recover.

Understanding Appendix Cancer Classification

For many years, appendix cancer was grouped under colon cancer because of its location in the digestive tract. This meant it was often treated using the same approaches as colorectal cancer. However, research over the past decade has revealed that appendix cancer is biologically and genetically distinct from colon cancer.

In 2010, the American Joint Committee on Cancer (AJCC) introduced a separate staging system for appendix cancer. Since then, updates—including the most recent AJCC Version 9 in 2023—have refined how different types of appendix tumors are classified and staged. These changes reflect growing knowledge about the unique behavior of appendix cancers, especially mucinous types like LAMNs (low-grade appendiceal mucinous neoplasms) and HAMNs (high-grade appendiceal mucinous neoplasms), which are now recognized as malignant.

Despite these advances, many treatment guidelines still fall under colon cancer protocols, and appendix cancer remains underrepresented in national databases and research. But change is happening. Experts and organizations are working to establish dedicated treatment pathways and clinical trials specifically for appendix cancer

At Appendix Cancer Canada, we advocate for greater recognition of appendix cancer as a distinct disease—because every patient deserves care that's tailored to their diagnosis.

Why This Difference Matters for Treatment

1. Molecular Differences Matter

A large genetic profiling study of over 700 appendix cancer samples found that mutations common in colon cancers—like TP53 and APC—are much less frequent in appendix cancers. In contrast, certain genes such as GNAS are more commonly mutated in mucinous appendiceal tumors.

2. Chemotherapy Protocols Are Borrowed but Inefficient
  • Because appendix cancer is so rare, doctors often default to colon cancer chemotherapy regimens for advanced disease.
  • However, molecular differences suggest that tailored treatments would likely be more effective and less toxic for appendix cancer. The NCI and researchers argue for the development of treatments designed specifically for appendix cancer.