# Peritoneal mesothelioma

Source: https://onco.cc/cancers/peritoneal-mesothelioma/  
OnCo record `peritoneal-mesothelioma` (Cancer). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Peritoneal mesothelioma grows in the lining of the abdomen, causing swelling, pain and fluid. Unlike its pleural cousin it is often treated with major surgery to strip the lining followed by heated chemotherapy washed through the abdomen, which can give long survival in fit patients with epithelioid disease.

## Summary

Peritoneal mesothelioma presents with abdominal distension from ascites, pain, weight loss or a mass found at surgery, and is diagnosed by laparoscopic biopsy with the same immunohistochemistry as pleural disease. Asbestos exposure is found in only a minority; BAP1 germline mutations account for some cases, and the disease is commoner in women than pleural mesothelioma. For fit patients with epithelioid histology and disease that can be removed, cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (HIPEC) is the standard in specialist centres and gives median survival of five years or more in series, though no randomised trial exists. Patients who are not candidates receive platinum-pemetrexed chemotherapy, with immunotherapy increasingly used on the basis of small trials and the pleural data. Well-differentiated papillary and multicystic forms behave almost benignly and are managed separately.

## Fields

- Kind: Cancer
- Last checked: 2026-09-16
- Also known as: Malignant peritoneal mesothelioma; MPeM; Diffuse malignant peritoneal mesothelioma
- Tags: subtype-page
- Group: gastrointestinal
- Burden: About one in ten mesotheliomas; a few hundred cases a year in the US. The asbestos link is weaker than in the pleura, it affects more women and younger people, and selected patients live many years after surgery.
- Subtypes: Epithelioid (most cases); Biphasic and sarcomatoid (rare, poor prognosis); Well-differentiated papillary mesothelial tumour (indolent); Multicystic mesothelioma (indolent)
- Biomarkers: Histology and peritoneal cancer index at laparoscopy; BAP1 loss (somatic and germline); Ki-67 (prognostic after surgery); Completeness of cytoreduction score

## Standard of care

- Diagnosis: CT, laparoscopy with biopsy and scoring of disease extent; germline BAP1 testing when young or with a family history. ([Mesothelioma](https://onco.cc/cancers/mesothelioma/))
- Resectable epithelioid disease, fit patient: Cytoreductive surgery with HIPEC in an experienced centre; long-term survival in a substantial fraction. ([HIPEC / PIPAC (intraperitoneal chemotherapy)](https://onco.cc/technologies/hipec/))
- Unresectable or unfit: Platinum-pemetrexed chemotherapy; nivolumab plus ipilimumab or pembrolizumab combinations extrapolated from pleural trials and small peritoneal series. ([Pemetrexed](https://onco.cc/drugs/pemetrexed/), [Nivolumab](https://onco.cc/drugs/nivolumab/), [Ipilimumab](https://onco.cc/drugs/ipilimumab/), [Pembrolizumab](https://onco.cc/drugs/pembrolizumab/))
- Indolent variants: Well-differentiated papillary and multicystic tumours: surgical removal and surveillance; systemic therapy rarely needed. ([Active surveillance](https://onco.cc/technologies/active-surveillance/))

## State of the art

- Cytoreduction with HIPEC, pioneered by Sugarbaker, turned a disease with a median survival under a year into one where a substantial fraction of selected patients live five years or more.
- Immunotherapy is being adopted from pleural mesothelioma with encouraging early results, and peritoneal patients are now included in mesothelin-directed trials.
- Registries and consortia have replaced case series as the evidence base because randomised trials are so hard to run in a disease this rare.

## Open problems

- No randomised trial has compared surgery plus HIPEC with systemic therapy.
- Selection for surgery relies on centre experience rather than validated criteria.
- Peritoneal patients were excluded from the pleural immunotherapy trials, so their benefit is inferred.

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Peritoneal_mesothelioma
- Wikipedia: https://en.wikipedia.org/wiki/Peritoneal_mesothelioma

## Connected records

- technologies: [Active surveillance](https://onco.cc/technologies/active-surveillance/), [HIPEC / PIPAC (intraperitoneal chemotherapy)](https://onco.cc/technologies/hipec/)
- ideas: [Antibody-drug conjugates for mesothelioma: why they have failed so far and how they could work](https://onco.cc/ideas/idea-adc-for-mesothelioma/)
- cancers: [Mesothelioma](https://onco.cc/cancers/mesothelioma/)
- drugs: [Ipilimumab](https://onco.cc/drugs/ipilimumab/), [Nivolumab](https://onco.cc/drugs/nivolumab/), [Pembrolizumab](https://onco.cc/drugs/pembrolizumab/), [Pemetrexed](https://onco.cc/drugs/pemetrexed/)

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