Colorectal Peritoneal Metastases (CPM): Key facts

Colorectal peritoneal metastases or CPM means a bowel cancer has spread (or metastasised) within the abdomen onto the peritoneum.

The peritoneum is the lining covering the surface of abdominal organs and the abdominal wall. In CPM, cells from the bowel cancer have broken free and spread onto surface of the peritoneum and other organs. In terms of colorectal cancer staging, CPM is stage 4.


o Between 5-10% of patients with a bowel cancer will already have peritoneal metastases and this is usually identified at the time of initial surgery. This is referred to as “synchronous colorectal peritoneal metastases”.

o Approximately 20-50% of patients develop CPM in the follow-up period after bowel cancer surgery. This is also referred to as “peritoneal recurrence” or “metachronous colorectal peritoneal metastases”.

Mr Umar Shariff is Consultant General and Colorectal Surgeon at Good Hope Hospital, University Hospitals Birmingham NHS Foundation Trust, and BMI The Priory and Edgbaston Hospitals.