Peritoneal Mesothelioma

What is Peritoneal Mesothelioma?

The peritoneum is the lining of the abdominal organs and abdominal wall. It is made of cells that can change their nature and give rise to a tumour called Mesothelioma. The peritoneal cells are similar to the cells of the lining of the lungs and thorax (pleura) which can also give rise to Mesothelioma. Peritoneal Mesothelioma is less common than pleural mesothelioma with only seven to ten percent of all mesotheliomas arising in the abdomen (Peritoneal Mesothelioma).

The team at Basingstoke Colorectal & Peritoneal Partners have great experience in the management of Peritoneal Mesothelioma having performed hundreds of Cytoreductive operations and Hyperthermic Intra-peritoneal Chemotherapy (HIPEC) for Peritoneal Mesothelioma. The team established, hosts and runs the international (UK and Ireland) Peritoneal Mesothelioma MDT where we review and advise on the management of Peritoneal Mesothelioma cases from around the UK and Ireland.

There are three major types of Peritoneal Mesothelioma:

Diffuse Malignant Peritoneal Mesothelioma

These tumours are made of malignant (cancer) cells that grow quickly and the body has little control over them. The tumours are usually more widely spread throughout the abdominal cavity. This group of mesothelioma tumours includes the following three types of mesothelioma:

Epithelioid: This is the most common type. Unfortunately it does not cause any specific symptoms until it has spread within the abdominal cavity. It tends to stay within the peritoneal cavity (abdomen) and most patients do not experience any symptoms until the later stages of the disease.

Sarcomatoid: This type is less common, it progresses more quickly and tends to has a more aggressive behaviour compared to the Epithelioid subtype. Unfortunately it tends to be less responsive to available treatments.

Biphasic (Epithelioid-Sarcomatoid): This is much more rare and is less aggressive that sarcomatoid but more aggressive that epithelioid mesothelioma. It sits in the middle of the other two subtypes of DMPM in both in its aggressiveness and response to treatments.

Low Grade Peritoneal Mesothelioma

These mesothelioma tumours are made of cells that tend to grow slower (low grade), tend to not directly invade other organs and also not travel to other parts of the body. These tumours are less aggressive compared to malignant mesothelioma but are not considered entirely benign. The are two subtypes:

Multicystic Mesothelioma (MM): These tumours are rare (three to five percent of all peritoneal mesotheliomas). They are fluid filled multiple cysts with thin walls and can vary in their cyst size. The main symptoms they tend to cause are pain, abdominal swelling, constipation and infertility in women. Multicystic Mesothelioma is more common in women of reproductive age but it can affect men and all age groups. In the majority of cases it is found as an incidental finding while investigating other abdominal symptoms and in the majority of cases the recommended treatment is active surveillance. In symptomatic patients surgery can be recommended in the form of removing all the cysts including the affected peritoneum with Cytoreductive Surgery (CRS) combined with heated intraperitoneal chemotherapy (HIPEC) also known as CRS and HIPEC.

Well Differentiated papillary peritoneal Mesothelioma (WDPM): This is also very rare and in the majority of patients is an incidental finding. It is again more common in women of reproductive age and tends to have a more indolent course but some patients it can have a malignant potential. As with MM it tends to be contained within the abdomen and tends not to spread to the rest of the body. Treatments approaches are tailored to the individual patient and can include surgery (CRS and HIPEC) to remove the affected areas of the peritoneum, active surveillance and systemic anti cancer treatment.

Localised Malignant Mesothelioma

This type of peritoneal mesothelioma is the least common and describes the rare solitary mesothelioma tumour in the abdomen without diffuse involvement of the rest of the peritoneal surfaces. This is rarely seen and in the majority of cases the treatment is surgical with CRS and HIPEC.

Diagnosis of Peritoneal Mesothelioma

The majority of patients with peritoneal mesothelioma have non specific symptoms such as abdominal discomfort/pain, non specific change of bowel habit, weight loss, nausea, abdominal distension or heaviness. Unfortunately the above symptoms are also reported by patients with much more common conditions such as irritable bowel syndrome or other benign conditions. Therefore it might take several months for patients to be diagnosed with this rare tumour.

In almost all patient a CT scan of the abdomen and pelvis will identify abnormal appearances (usually thickening) of the peritoneum, fluid in the abdomen (ascites) or pick up the characteristic cysts seen in Multicystic Mesothelioma. Following this usually a biopsy may be organised that can be done under imaging (usually) ultrasound guidance to take tissue or fluid to be looked under the microscope to confirm the diagnosis.

Unfortunately in some cases these biopsies might not be enough and a small operation under general anaesthetic might be performed to look directly into the peritoneal cavity with a camera called laparoscopy. This operation allows bigger tissue biopsies which usually can confirm or exclude mesothelioma.

Some patients are diagnosed when they are having an operation in their abdomen for another reason such as gallstones, appendicitis, hernia repairs etc and the surgeons notice the abnormal peritoneal appearances and take biopsies.

Treatment for Peritoneal Mesothelioma

In general the treatment for Peritoneal Mesothelioma is dictated by each patient’s specific circumstances and is dependent on the mode of presentation, patient fitness, type of Mesothelioma and distribution of disease. The choices of treatment include systemic anti cancer treatment, surgery and period of surveillance.

Systemic anti cancer treatment

This type of treatment includes the use of a combination of chemotherapy drugs that aim to kill cancer cells. These drugs (most commonly used Cisplatinum, Carboplatin, Pemetrexed, Gemcitabine) are mostly used to treat malignant subtypes (both diffuse or localised) and aim to shrink the tumours and usually do not achieve cure. These are toxic drugs and have significant side effects and the patient has to have a reasonable performance level to be able to tolerate them.

Immunotherapy

In recent years immunotherapy has been shown to have remarkable success in treating other cancer types such as melanoma and lung cancers. Recent trials using immunotherapy in Mesothelioma have also shown very positive results and immunotherapy is consider the first line of systemic anticancer treatment for mesothelioma. It can be used as double agent (two different drugs) or single agent depending on specific clinical factors.
Its mechanism of action depends on the individual drug but in general these drugs manipulate or augment the body’s own immune system to try and make it easier for the immune system to kill cancer cells.

Surgery

The aim of surgery is to remove all visible abnormal tissues, a term called complete cytoreduction. This is usually combined with the application of a hot chemotherapy solution in the peritoneal cavity at the time of cytoreductive surgery a procedure known as CRS and HIPEC. This procedure is performed in specialists centres such as our unit here in Basingstoke in very carefully selected patients with specific types of peritoneal mesothelioma. CRS and HIPEC is usually used for patients for which the team predict that they will be able to remove all visible disease and therefore will give the patient a significant chance of cure compared to systemic treatments.

The long term outcomes after complete cytoreduction and HIPEC largely depend on the sub type of mesothelioma (LGPM and Epithelioid having the best predicted outcomes) and whether complete cytoreduction has been achieved or not.

In some patients a debulking operation maybe indicated if they have protracted symptoms and a full cytoreduction is not possible. These decisions are made based on each patient specific disease types and circumstances.

Basingstoke Colorectal & Peritoneal
The Hampshire Clinic
Basing Road
Basingstoke RG24 7AL

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01256 354747