Classification of extensiveness/peritoneal cancer index (PCI)
Peritoneal cancer varies from nearly microscopic to kilogram scale interperitoneal tumor tissue. It is therefore important to have a classification system to compare studies from various treatment centers.
The most common indication in extensiveness of surface for peritoneal disease is developed by Sugar Baker in the US around 1990.The abdomen is separated into 9 regions. The extent in each region is described based on the size of the lesion. The small intestine is separated in the same way into 4 regions. In each of the 13 areas, the size of the lesion is described in lesion score (LS), on a scale from 0 to 3. This is then calculated as Peritoneal Carcinomatosis Index (PCI), which is the sum of the lesion sizes from all 13 areas. PCI index will be a number between 0 and 39.
Regions and scoring used for calculating Peritoneal Carcinomatosis Index (PCI).
Classification of surgical result/degree of cytoreduction
There are multiple classification systems. Some systems indicate complete surgical radicality (R0) which is equivalent to removal of all visible tumor tissue. In another widely used classification system, the cytoreductive surgery is indicated as CC-0 if there is no residual tumor, CC-1 if the largest residual tumor is less than 2.5 mm, CC-2 between 2.5 mm-2.5 cm and CC-3 indicates larger residual lesions. The background for this staging is that chemotherapy will apparently diffuse 2-3 mm into the tissue.