This study would like to assess the efficacy of pressurised intraperitoneal aerosol chemotherapy (PIPAC). This technique delivers chemotherapy directly into the abdomen via a less invasive laparoscopic or 'keyhole' form of surgery. This type of chemotherapy takes the form of an aerosol, similar to the spray of a deodorant for example. The aerosol is administered into the abdomen under pressure, pushing the chemotherapy deeper into the tissues and cancer. This approach does not involve any surgical removal of the cancer.

This study aims to assess the efficacy of a novel intervention for advanced colorectal cancers with peritoneal metastases (i.e. cancers of the colon or rectum which have spread to the internal lining of the abdomen).

Patients diagnosed with peritoneal metastases usually first undertake a period of neoadjuvant systemic chemotherapy prior to consideration of cytoreductive surgery and subsequent hyperthermic intraperitoneal chemotherapy (CRS-HIPEC). If the extent of peritoneal disease remains too significant then CRS-HIPEC is contraindicated.

Not all patients are suitable for cytoreductive surgery and subsequent hyperthermic intraperitoneal chemotherapy (CRS-HIPEC). CRS-HIPEC involves a large cut down the length of the abdomen, surgery to cut away as many of the structures affected by cancer as possible then the bathing the abdomen in heated chemotherapy. This is associated with a considerable risk of complications and a not insignificant risk of death. As such there is a significant unmet need for less invasive effective treatments for patients with extensive colorectal peritoneal metastases (CPM).

This study would like to assess the efficacy of pressurised intraperitoneal aerosol chemotherapy (PIPAC). This technique delivers chemotherapy directly into the abdomen via a less invasive laparoscopic or 'keyhole' form of surgery. This type of chemotherapy takes the form of an aerosol, similar to the spray of a deodorant for example. The aerosol is administered into the abdomen under pressure, pushing the chemotherapy deeper into the tissues and cancer. This approach does not involve any surgical removal of the cancer.

It is an additional treatment to the standard intravenous or oral chemotherapy which would otherwise be administered in isolation for the selected patients. PIPAC would be administered across multiple sessions assuming no disease progression was identified. It can be used in patients undertaking neo-adjuvant systemic chemotherapy before CRS- HIPEC or used throughout treatment for those patients deemed not suitable for CRS-HIPEC.

Inclusion Criteria:

1. Patients with CPM with expected life expectancy of > 6 months.
2. ECOG Scale of Performance Status (PS) scores 0 or 1.
3. 15 mile catchment area to facilitate overseeing systemic chemotherapy administration
4. Concomitant systemic chemotherapy regimens with FOLFIRI, FOLFOX, Mitomycin C & Fluorouracil, Capecitabine (excluding Lonsurf) or without systemic chemotherapy if no systemic options available to patient
5. Neutrophil count on or just before chemotherapy due date of >1.5

Exclusion Criteria:

1. Age <18
2. MDT decision that patient not suitable for PIPAC
3. Decision by Preoperative Assessment Department or Consultant Anaesthetist that patient not fit for general anaesthesia and / or laparoscopy
4. Clinically evident gross ascites
5. Bowel obstruction
6. Bevacizumab as part of systemic chemotherapy regime - time from chemotherapy to surgery would be too long for PIPAC to be feasible
7. Previous bone marrow suppression due to chemotherapy given risk of post-operative neutropenia