Neo-adjuvant radiotherapy in rectal cancer

Table 1 Tumor node metastasis-7 classification (2010) with subclassification of stage T3

TNM	Extension to
Tis	Carcinoma in situ: intraepithelial or invasion of lamina propria
T1	Submucosa
T2	Muscularis propria
T3	Subserosa/perirectal tissue
T3a1	Less than 1 mm
T3b	1-5 mm
T3c	5-15 mm
T3d	15+ mm
T4	Perforation into visceral peritoneum (a) or invasion to other organs (b)
N1	1-3 regional nodes involved
N1a	1 lymph node
N1b	2-3 lymph nodes
N1c	Small deposits in the fat
N2	4 or more regional nodes involved
N2a	4-6 lymph nodes
N2b	7 or more lymph nodes
M1	Distant metastases
M1a	1 distant organ or set of lymph nodes
M1b	More than 1 organ or to the peritoneum

¹This subclassification is based upon an evaluation using magnetic resonance imaging prior to treatment decision is clinically valuable, and recommended in this review. It can be used also in the histopathological classification but is not validated and not incorporated in TNM version 7. TNM: Tumor node metastasis.