Appendix cancer: types, symptoms, diagnosis and treatment

Appendix cancers are uncommon and often only found during tests or treatments for other conditions. Neuroendocrine Cancer UK says symptoms, if they occur, may be the same as for suspected appendicitis, and that they are rarely associated with a neuroendocrine cancer syndrome. NHS 111 Wales says a tumour in the appendix may only be found when the appendix is being removed for another reason.

For pseudomyxoma peritonei, Cancer Research UK says some people have no symptoms, and others have pain in the abdomen or pelvis, swelling and bloating, changes in bowel habits, a hernia, loss of appetite, a feeling of fullness or difficulty becoming pregnant. It notes the condition develops very slowly, so symptoms may take years to appear.

Cancers of the appendix are rare and come in different types that behave differently. Neuroendocrine Cancer UK says appendix neuroendocrine neoplasms make up the majority of appendiceal neoplasms. The appendix sits near where the large and small bowel meet, in the lower right abdomen, and has no clearly identified function in humans.

Cancer Research UK describes a second group: pseudomyxoma peritonei (PMP) usually begins as a small polyp-like growth called a low grade appendiceal mucinous neoplasm (LAMN). It makes mucus that collects in the abdomen as a jelly-like fluid, sometimes called jelly belly. It is regarded as borderline malignant and does not usually spread through the blood or lymph, but grows and spreads within the abdomen.

Many appendix tumours are diagnosed after the appendix has been removed and examined under the microscope. For a neuroendocrine tumour, Neuroendocrine Cancer UK lists tests that may be used, including blood and urine tests (such as chromogranin A and serotonin breakdown products), CT or MRI scans, specialised PET/CT scans and colonoscopy, with pathology testing to grade the tumour.

For pseudomyxoma peritonei, Cancer Research UK says it can be hard to diagnose and is sometimes found by accident. Ultrasound, CT and MRI scans are used, and doctors can often only diagnose it properly after an operation to look into the abdomen (a laparotomy). In women it can be confused with ovarian cancer.

Treatment depends on the type. For neuroendocrine tumours, Neuroendocrine Cancer UK says appendiceal NENs less than 1cm and completely removed by surgery often need no further treatment or follow-up. If the tumour is larger, shows evidence of spread, is at the base of the appendix or the appendix has burst, further follow-up or treatment may be needed. It says there is consensus that all NEN patients should be reviewed by a specialist multidisciplinary team.

For pseudomyxoma peritonei, Cancer Research UK says the main treatment is surgery and chemotherapy together: cytoreductive surgery (CRS) with hyperthermic intraperitoneal chemotherapy (HIPEC), where heated chemotherapy is put into the abdomen during the operation. You have to be well enough, and the surgeon needs to be able to remove the disease without affecting vital organs.

It describes this as major surgery lasting around 10 hours, with a stay of 2 to 3 weeks and at least 6 months before you are fully active again. About 30 in 100 people have complications and about 20 in 100 need a stoma. Debulking surgery to remove as much disease as possible, or chemotherapy, may be used instead, and some people are monitored with blood tests and scans (watch and wait) if the cancer is small and slow growing.

The Peritoneal Malignancy Institute in Basingstoke says that assessment and management of pseudomyxoma peritonei has been commissioned from Basingstoke and North Hampshire Hospital since April 2000 and from The Christie in Manchester since 2002, as highly specialised services commissioned on behalf of NHS England.

It describes the condition as having an incidence of about two cases per million per year, arising mainly from the appendix, and being at best borderline malignant but varying in aggressiveness and clinical course.

Follow-up depends on the tumour. Neuroendocrine Cancer UK says that after appendicectomy, a well-differentiated grade 1 tumour under 1cm, completely removed with no further disease, needs no follow-up beyond the routine post-operative check, whereas tumours of 1 to 2cm may have a single post-operative CT scan. It says risk factors such as a tumour at the base of the appendix lead to longer-term follow-up, and that follow-up is tailored to you.

Cancer Research UK says watch-and-wait can feel hard to cope with because it can feel as if no action is being taken, and that debulking surgery will not cure PMP and the disease is likely to come back unless the whole cancer can be removed.

Persistent pain, swelling or bloating in the abdomen, or a change in bowel habit should be checked by a GP. Appendix cancer can look like appendicitis; the NHS says appendicitis symptoms usually start with pain in the middle of the abdomen around the belly button, and to call 999 or go to A&E for severe abdominal pain.

On the NHS, appendix tumours are typically picked up through the appendicitis pathway or investigated by a bowel or general surgical team, with referral to a neuroendocrine tumour or peritoneal malignancy specialist centre where needed. Some people also seek a private second opinion. Ask whether your case has been discussed at a specialist multidisciplinary team meeting.