Table 1.

TNM score (adopted fromRef. [32]). TNM: Tumour node metastasis.

DEFINITION OF TNM
Primary Tumor (T)
TX	Primary tumor cannot be assessed
T0	No evidence of primary tumor
Tis	Carcinoma in situ (Bowen's disease, high grade squamous intraepithelial lesion HSIL, anal intraepithelial neoplasia AIN II-III
T1	Tumor 2 cm or less in greatest dimension
T2	Tumor more than 2 cm but not more than 5 cm in greatest dimension
T3	Tumor more than 5 cm in greatest dimension
T4	Tumor of any size invades adjacent organ(s)*
*Note: Direct invasion of the rectal wall, perirectal skin, subcutaneous tissue or the sphincter muscle(s) is not classified as T4.
Regional Lymph Nodes (N)
NX	Regional lyph nodescannot be assessed
N0	No regional lyph nodes metastasis
N1	Metastasis in perirectal lyph node(s)
N2	Metastasis in unilateral internal iliac and/or inguinal lyph node(s)
N3	Metastasis in perirectal and inguinal lymph nodes and/or bilateral internal iliac and/or inguinal lymph nodes
Distant Metastasis (M)
M0	No distant metastasis
M1	Distant metastasis

ANATOMIC STAGE/PROGNOSTIC GROUPS
Stage	T	N	M
0	Tis	N0	M0
I	T1	N0	M0
II	T2	N0	M0
	T3	N0	M0
IIIA	T1	N1	M0
	T2	N1	M0
	T3	N1	M0
	T4	N0	M0
IIIB	T4	N1	M0
	Any T	N2	M0
	Any T	N3	M0
IV	Any T	Any N	M1