Table 1

 Dukes B prognostic model

Petersen index (PI)
EquationPI  =  (peritoneal involvement) + (vascular invasion) + (margin involvement) + (tumour perforation)
VariablesPeritoneal involvement  = 1Margin involvement  = 1
Vascular invasion  = 1Tumour perforation  = 2
RiskLow risk PI between 0 and 1
High risk PI between 2 and 5