Appendiceal cancer (cancer of the appendix): types, symptoms, diagnosis and treatment

The appendix is a small thin tube attached to the large bowel on the lower right side of the abdomen. Neuroendocrine Cancer UK describes it as being near the junction where the large and small bowel meet, and notes it has no clearly identified function in humans. Cancer Research UK says the role of the appendix is unclear.

Appendiceal cancer is a group of rare tumours that start in the appendix. The two groups described most clearly in UK patient information are neuroendocrine neoplasms (NENs), which start in neuroendocrine cells, and mucinous tumours, such as a low grade appendiceal mucinous neoplasm (LAMN), which can cause pseudomyxoma peritonei (PMP).

Neuroendocrine Cancer UK says appendix NENs are uncommon but make up the majority of appendiceal neoplasms. It explains that NETs (neuroendocrine tumours) are well-differentiated and tend to have a slow to moderate growth pattern, while NECs (neuroendocrine carcinomas) are poorly differentiated and tend to grow rapidly. The sources read for this page do not give national incidence figures for appendiceal cancer, so none are quoted.

Neuroendocrine tumours of the appendix are usually small. Neuroendocrine Cancer UK says most are located at the tip of the appendix and are diagnosed at an early stage, meaning curative surgery can be performed, while a small proportion are at the base of the appendix and may need further and longer-term interventions.

Mucinous tumours behave differently. Cancer Research UK explains that pseudomyxoma peritonei usually begins in the appendix as a small growth called a polyp, known as a LAMN, which is different from the polyps that cause bowel cancer. The cells make mucus, which collects in the abdomen as a jelly-like fluid called mucin. Cancer Research UK says it usually grows slowly and spreads inside the abdomen along the peritoneum, rather than through the blood or lymphatic system to other parts of the body.

Macmillan says PMP usually starts in the appendix but can start in another part of the bowel, the bladder or the ovaries. Because it develops very slowly, Cancer Research UK says it can be years before there are symptoms, and it has usually spread beyond the appendix before diagnosis. Pseudomyxoma peritonei has its own guide on this site; this page focuses on the appendix as the starting point.

Many appendix tumours cause no symptoms and are found incidentally. When symptoms occur, Neuroendocrine Cancer UK says they may be the same as for suspected appendicitis and are rarely associated with a neuroendocrine cancer syndrome.

The NHS describes appendicitis as pain that usually starts around the belly button and after a few hours moves to the lower right side of the abdomen and gets worse, sometimes with feeling or being sick, loss of appetite, a high temperature and constipation or diarrhoea. It says appendicitis needs urgent treatment in hospital.

For mucinous tumours, Macmillan lists a gradual increase in waist size, a hernia, loss of appetite, unexplained weight gain, tummy pain, pelvic pain and changes in bowel habit among symptoms of PMP. Cancer Research UK adds swelling and bloating, a feeling of fullness and, in women, that PMP can sometimes be confused with ovarian cancer.

• The NHS says to ask for an urgent GP appointment or get help from NHS 111 if you have tummy pain that is gradually getting worse, does not go away, or moves to the lower right side.

• The NHS says to call 999 or go to A&E for severe tummy pain, or confusion, blotchy or paler than usual skin or difficulty breathing, which could be signs of sepsis.

• See a GP for a gradually increasing waist size, a new hernia or persistent bloating and unexplained weight change, even though these have many other causes.

The commonest route is incidental. Neuroendocrine Cancer UK says appendix NENs are usually discovered following treatment, for example a histology review following appendicectomy, meaning the removed appendix is examined under the microscope. Cancer Research UK says doctors sometimes find PMP by accident during treatment for other conditions.

Once a tumour is identified, further tests depend on the type. For neuroendocrine tumours, Neuroendocrine Cancer UK lists blood and urine tests (including full blood count, liver and kidney function, tumour markers such as CEA, chromogranin A and urinary or serum 5-HIAA), CT or MRI scans, nuclear medicine scans such as octreotide SPECT or gallium-dotatate PET/CT, endoscopy including colonoscopy, and specialised pathology tests. Grading, which describes how fast the tumour is growing and may be referred to as Ki67 or mitotic index in clinic letters, runs from grade 1 (slow growing) to grade 3 (more aggressive).

For PMP, Cancer Research UK lists ultrasound, CT and MRI scans, and says doctors can sometimes only diagnose it properly after an operation to look into the abdomen. Macmillan adds that a biopsy may be taken during keyhole surgery (laparoscopy) or guided by CT or ultrasound.

Neuroendocrine Cancer UK says treatment is personalised to the type of NEN and may involve removal, control of disease by slowing or stopping growth, or easing of symptoms. Appendiceal NENs of less than 1cm that are completely removed by surgery often do not need any further treatment or follow-up and are essentially cured. If the tumour is larger, shows evidence of spread, is found at the base of the appendix or the appendix has burst, further follow-up or treatment may be needed. Its follow-up guidance mentions that evidence of further disease such as enlarged nearby lymph nodes leads to a recommendation for a right hemicolectomy and lymph node assessment.

For PMP, Macmillan says the main treatments are surgery and heated chemotherapy given directly into the peritoneum (HIPEC). Cytoreductive surgery aims to remove as much of the PMP as possible, followed by the heated chemotherapy. Macmillan says this is done at two UK centres, Basingstoke and North Hampshire Hospital and the Christie Hospital in Manchester. If PMP is small or growing slowly, watchful waiting may be used and treatment may not start straight away, with regular scans and check-ups.

Cancer Research UK says treatment depends on where the cancer is and your general health. Whatever the type, the plan is made by a specialist team, and Neuroendocrine Cancer UK stresses that your care team should explain options with written and verbal information so you can make an informed choice.

In the UK, appendix tumours are usually identified through NHS surgery and pathology, and rarer or more complex cases are discussed by specialist multidisciplinary teams, sometimes at a regional or national centre. Macmillan notes that you may need to travel to a specialist centre for PMP surgery.

Some people seek a private second opinion on pathology or the treatment plan. It is reasonable to ask your surgeon or clinical nurse specialist for copies of your histology report and scans so that any second opinion is based on the same information.