Peritoneal carcinomatosis: what it means, symptoms and treatment options in the UK

The peritoneum is a thin lining of the abdomen. Cancer Research UK explains that the abdomen contains organs such as the stomach, bowel, pancreas, liver, spleen and kidneys, which sit in the peritoneal space lined by the peritoneum, made up of two layers. One lines the wall of the space and the other covers the organs.

Peritoneal carcinomatosis is the name used when cancer cells from a cancer elsewhere in the abdomen have spread across this lining. NHS England's policy gives the appendix, bowel, rectum and ovaries as examples of where the original cancer may begin, and a Scottish NHS page describes cancers of the bowel and appendix that have spread to the lining of the abdomen. It is different from cancers that start in the peritoneum itself, such as peritoneal mesothelioma, or from pseudomyxoma peritonei, which the policy explicitly treats separately.

The sources describe the complications in general terms. NHS England's policy lists bowel obstruction, accumulation of fluid in the peritoneal cavity and pain. Cancer Research UK describes the symptoms of ascites in more detail, noting that it can make the tummy feel tight and uncomfortable, often developing over a few weeks but sometimes over a few days.

• Clothes feeling tighter and bloating of the tummy.

• Abdominal pain or back pain.

• Loss of appetite, indigestion, constipation, or feeling or being sick.

• Needing to pass urine often.

• Breathlessness, because pressure on the diaphragm can affect the lungs.

• Tiredness and weakness (fatigue), and difficulty sitting comfortably and moving around.

Cancer Research UK says it is important to speak to your doctor or specialist nurse if you have symptoms of ascites. If you already have a cancer diagnosis, tell your cancer team promptly about a swollen or tight tummy, new pain or breathlessness. NHS England describes bowel obstruction as a recognised complication of this condition. The sources reviewed do not set out emergency thresholds, so if symptoms suddenly worsen contact your cancer team or NHS 111, and use 999 or A&E for a medical emergency.

There is no single UK patient page for peritoneal carcinomatosis itself, so this section relies on related sources. Cancer Research UK says that when fluid is suspected the doctor examines you, asks about symptoms and may arrange an ultrasound scan, blood tests to check general health and kidney and liver function, a CT scan, and a sample of the fluid taken through a needle (paracentesis) to check for cancer cells or infection.

Because treatment depends on where the cancer started and how far it has spread, assessment is led by a specialist cancer team. NHS Tayside says that suitability for specialist surgery requires a detailed assessment by the surgeon and team.

Cancer Research UK says the main treatment for ascites is draining the fluid, called an abdominal paracentesis. A doctor numbs the skin, passes a thin tube into the fluid, which drains into a bag, sometimes guided by ultrasound. The tube may stay in for a few hours, or a few days if there is more than a couple of litres. Draining relieves symptoms in 90 out of 100 people, though fluid can collect in pockets that make drainage harder.

Possible side effects include low blood pressure if fluid drains too quickly, kidney problems after draining a large volume, pain, infection in the abdomen (peritonitis), and tube blockage. Medicines and cancer drugs to control the cancer may also help prevent fluid building up, and some people have a long-term drain.

Peritoneal carcinomatosis has traditionally been regarded as an end-stage feature of abdominal cancers, with median survival of 6 months or less identified in the literature, according to NHS England's 2013 policy. The same policy describes cytoreductive surgery plus hyperthermic intraperitoneal chemotherapy (CRS and HIPEC) as aiming to provide curative treatment through complete removal of the tumour.

Hampshire Hospitals says that patients with colorectal peritoneal metastases were traditionally treated with palliative intent, and that recent evidence shows CRS and HIPEC can result in improved survival rates. NHS Tayside describes the treatment as extensive surgery to remove all visible cancer, followed by tubes placed in the abdomen through which warmed chemotherapy is circulated for 45 minutes and then washed out. It is a long operation that can take several hours.

It is not suitable for everyone. NHS England's policy covers peritoneal carcinomatosis secondary to colorectal, gastric, pancreatic and ovarian cancer, but says evidence of benefit is clearest for colorectal cancer in selected patients. Hampshire Hospitals says NHS England decided in 2015 not to routinely commission the procedure for peritoneal mesothelioma, and the 2013 policy excludes pseudomyxoma peritonei, which has its own highly specialised service.

In England, Hampshire Hospitals says CRS and HIPEC for colorectal peritoneal metastases has been commissioned by NHS England specialised commissioning from its Peritoneal Malignancy Institute at Basingstoke since 2013, without the need for an individual funding request. The NHS England policy referred to two national centres, and Hampshire Hospitals notes that capacity may need to grow. In Scotland, NHS Tayside says Ninewells Hospital is the only centre offering HIPEC. Referral is made by your cancer team after assessment.

The outlook depends on where the cancer started and how far it has spread, and your team can discuss what applies to you. NHS England's policy acknowledges that the condition is associated with short survival and poor quality of life, while stating there is a long-term survival benefit for selected colorectal patients. Where cure is not possible, treatment focuses on controlling symptoms such as fluid and obstruction.

Cancer Research UK provides information and a nurse helpline, and your cancer team can explain what support is available.