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Appendix Cancer (Pseudomyxoma Peritonei (PMP))

Appendix cancer occurs when cells in the appendix become abnormal and keep growing and form a mass or lump called a tumour.

The type of cancer is defined by the particular cells that are affected and can be benign (non-cancerous) or malignant (cancerous). Malignant tumours can spread to other parts of the body through the bloodstream or lymph vessels and form another tumour at a new site. This new tumour is known as secondary cancer or metastasis.

Pseudomyxoma peritonei is (PMP) a rare tumour that grows slowly and causes a build-up of mucin (a jelly-like substance) in the abdomen and pelvis, giving rise to the name "jelly belly". Several other diseases may also be associated with "jelly belly", including mucinous adenocarcinoma, or may resemble features of PMP, including mucinous tumours in the bowel.

PMP often starts in the appendix but can also start in other organs like the large bowel and ovary. While it doesn't spread to other parts of the body, PMP can put pressure on important organs as it continues to grow, and this may cause problems.

Treatment

The main treatments for appendix cancer and PMP are surgery and chemotherapy. These can be given alone or in combination and are an effective treatment with a little over 60% of patients receiving both cytoreductive surgery and HIPEC surviving beyond ten years. PMP may not be treated straight away if the tumour is small and growing slowly; in this case, it will be observed and monitored regularly, an approach known as active surveillance.

Surgery

Surgery is the primary treatment for appendix cancer, especially for people with early-stage disease otherwise in good health. The type of operation depends on the location and stage of the tumour.

PMP is usually treated with surgery: either cytoreductive surgery followed by chemotherapy (HIPEC) when aiming to cure PMP. If the cancer cannot be treated effectively, debulking surgery may be used instead to remove as much of the tumour as possible to reduce symptoms. Debulking surgery may be done again if the tumour grows back.

Types of surgery

Appendectomy – Surgery to remove the appendix. Often used for early stage appendiceal NETs.

Hemicolectomy – Surgery to remove a small part of the large bowel next to the appendix; surrounding lymph nodes and blood vessels may also be removed during the procedure. Often used for appendiceal NETs at risk of spreading or appendix cancers that are not neuroendocrine.

Cytoreductive surgery (CRS or peritonectomy) – Surgery to remove all visible tumour from the abdominal cavity; part of the bowel and other organs including gallbladder, spleen, stomach and kidney may also be removed. In females, the uterus, ovaries and fallopian tubes may be removed. In males the seminal vesicles may be severed. Cytoreductive surgery is often used for late-stage appendix cancer and PMP Chemotherapy.

If part of the bowel is removed during surgery, the surgeon will usually join it back together. If this isn't possible, you may need a stoma where the end of the intestine is brought through an opening (the stoma) made in your abdomen and stitched onto the skin to allow faeces to be removed from the body and collected in a bag. The stoma may be temporary or permanent, depending on the amount of bowel that has been removed.

Chemotherapy

Chemotherapy is the use of drugs to kill or slow the growth of cancer cells. You may have one chemotherapy drug, or a combination of medicines as different drugs can destroy or shrink cancer cells in different ways.

Radiation therapy

Radiation therapy (also known as radiotherapy) uses high energy rays to destroy cancer cells. It may be used for appendix cancer when it has spread to other parts of the body, such as the bone. Radiation therapy can shrink the cancer and relieve symptoms.

Risk factors

The causes of appendix cancer and PMP are not known. There are no clear risk factors and neither appear to run in families. Increasing age, however, can increase the risk of appendix cancer.

Appendix cancer is rare, with 0.12 cases per 1,000,000 people each year being reported for primary malignancies (cancer that first develops in the appendix). The most common types are seen in middle-aged people, with the typical age at diagnosis about 40 to 60 years. 

PMP is also rare, with about 1 or 2 cases per 1,000,000 people each year. It is more likely to be diagnosed in people aged 40 years or over. Women may be diagnosed slightly more often and at an earlier stage than men after a mass or lump is found in their ovary.

Early symptoms

Appendix cancer may not cause symptoms in its early stages. However, some people may experience symptoms such as:

  • Appendicitis (lower right abdominal pain).
  • Gradual increase in waist size.
  • The build up of fluid in the abdomen.
  • Bloating.
  • Changes in bowel habits.
  • Hernia.
  • Ovarian mass or lump.

PMP is also difficult to detect, and symptoms may take a while to develop. Symptoms that some people may experience include:

  • Abdominal or pelvic pain.
  • Gradual increase in waist size.
  • Bloating.
  • Changes in bowel habits.
  • Hernia.
  • Loss of appetite.

Not everyone with the symptoms above will have cancer but see your general practitioner (GP) if you are concerned. 

Diagnosis/diagnosing

Appendix cancer is often found during abdominal surgery for a different condition or after an appendectomy (surgical removal of the appendix) for a suspected case of appendicitis. Similarly, PMP is often discovered when investigating a different condition.

If your doctor thinks you may have appendix cancer or PMP, they will perform a physical examination and conduct specific tests. If the results suggest that you may have appendix cancer or PMP, your doctor will refer you to a specialist to carry out more tests. 

Blood tests

Including a full blood count to measure your white blood cells, red blood cells, platelets and tumour markers (chemicals produced by cancer cells).

CT (computerised tomography) or MRI (magnetic resonance imaging) scans

Special machines are used to scan and create pictures of the inside of your body. Before the scan you may have an injection of dye (called contrast) into one of your veins, which makes the pictures clearer. During the scan, you will need to lie still on an examination table. For a CT scan the table moves in and out of the scanner which is large and round like a doughnut; the scan itself takes about 10 minutes. For an MRI scan the table slides into a large metal tube that is open at both ends; the scan takes a little longer, about 30–90 minutes to perform. Both scans are painless.

Ultrasound scan

Soundwaves are used to create pictures of the inside of your body. For this scan, you will lie down and a gel will be spread over the affected part of your body. A small device called a transducer is moved over the area. The transducer sends out soundwaves that echo when they encounter something dense, like an organ or tumour. The ultrasound images are then projected  onto a computer screen. An ultrasound is painless and takes about 15–20 minutes.

Diagnostic laparoscopy

A thin tube with a camera on the end (laparoscope) is inserted under sedation into the abdomen to view inside the cavity.

Biopsy

Removal of some tissue from the affected area for examination under a microscope. The biopsy may be done in one of two ways. In a core needle biopsy, a local anaesthetic is used to numb the area, then a thin needle is inserted into the tissue under ultrasound or CT guidance. An open or surgical biopsy is done under general anaesthesia. The surgeon will cut through the skin and use a tiny instrument with a light and camera (laparoscope) to view the affected area and use another instrument to take a tissue sample.

Prognosis (Certain factors affect the prognosis and treatment options)

Doctors estimate appendiceal cancer survival rates by how people with appendiceal cancer have done in the past. Because there are so few appendiceal cancer patients, these rates may not be very accurate.

Each person is different and prognosis will depend on many factors, such as:

  • The type of appendiceal cancer that you have.
  • Where the tumor is in your body.
  • If the cancer has spread to other parts of your body.
  • How much of the tumor was taken out during surgery.

The five year survival rate for neuroendocrine tumors of the appendix and other low-grade tumors is between 67% to 97%. However, the 5-year survival rate for more advanced appendiceal cancer or that which has spread to other parts of the body can be much lower.

References

Some references are to overseas websites. There may be references to drugs and clinical trials that are not available here in Australia.