T: primary tumor
TXPrimary tumor cannot be assessed
T0No evidence of primary tumor
TisCarcinoma in situ
T1Tumor invades submucosa
T2Tumor invades muscularis propria
T3Tumor invades subserosa or into non peritonealized pericolic / perirectal tissues
T4aTumor perforates visceral peritoneum
T4bTumor directly invades other adjacent structures
N: regional lymph nodes
NXRegional lymph nodes cannot be assessed
N0No regional lymph node metastasis
N1aMetastasis in 1 regional lymph node
N1bMetastasis in 2-3 regional lymph nodes
N1cTumour deposits in the subserosa or in non peritonealized perirectal soft tissue without regional lymph node metastasis
N2aMetastasis in 4-6 regional lymph nodes
N2bMetastasis in 7 or more regional lymph nodes
M: distant metastasis
M0No distant metastasis
M1aMetastasis confined to one organ (liver, lung, ovary, non regional lymph nodes) without peritoneal metastases
M1bMetastasis in more than one organ
M1cMetastasis to the peritoneum with or without other organ involvement