"Tx: primary tumour cannot be assessed"
"T0: no evidence of primary tumour"
"Tis: carcinoma in situ: intraepithelial or invasion of lamina propria"
"T1: tumour invades submucosa"
"T2: tumour invades muscularis propria"
"T3: tumour invades through the muscularis propria into the subserosa or into non-peritonealised perirectal tissues"
"T3a: tumour extends"
"T3b: tumour extends 1-5 mm beyond muscularis propria 4"
"T3c: tumour extends 5-15 mm beyond muscularis propria 4"
"T3d: tumour extends 15 mm beyond muscularis propria 4"
"T4: tumour invades directly into other organs or structures and/or perforates visceral peritoneum"
"T4a: tumour penetrates to the surface of the visceral peritoneum"
"T4b: tumour directly invades or is adherent to other organs or structures"
"Nx: regional nodes cannot be assessed"
"N0: no regional lymph node metastases"
"N1: metastasis in 1-3 regional (perirectal) lymph nodes"
"N1a: metastasis in 1 regional lymph node"
"N1b: metastasis in 2-3 regional lymph nodes"
"N1c: tumour deposit(s) in the subserosa, mesentery, or non-peritonealised pericolic or perirectal tissues without regional nodal metastasis"
"N2: metastasis in 4 or more regional lymph nodes"
"N2a: metastasis in 4-6 regional lymph nodes"
"N2b: metastasis in 7 or more regional lymph nodes"
"Mx: cannot be assessed"
"M0: no distant metastasis"
"M1: distant metastasis"
"M1a: metastasis confined to one organ or site (for example, liver, lung, ovary, non-regional node) without peritoneal metastases"
"M1b: metastases in more than one organ"
"M1c: metastasis to the peritoneum with or without other organ involvement"
"stage 0: Tis N0 M0"
"stage I: T1-2, N0 M0"
"IIa: T3, N0, M0"
"IIb: T4a, N0, M0"
"IIc: T4b, N0, M0"
"IIIa: T1-2, N1, M0"
"IIIb: T3-4, N1, M0"
"IIIc: T3-4b, N2, M0"
"stage IV: any T, any N, M1"
"stage 1: tumour confined to bowel wall with intact outer muscularis propria"
"stage 2: tumour replaces muscularis propria but does not extend into intersphincteric plane"
"stage 3: tumour invades intersphincteric plane or lies within 1 mm of levator muscles"
"stage 4: tumour invades external anal sphincter and is within 1 mm and beyond levators with or without invading adjacent organs"
"SM1: tumour invasion into upper third of submucosa"
"SM2: tumour invasion into middle third of submucosa"
"SM3: tumour invasion into lower third of submucosa"
"T3d: tumour extends 15 mm beyond muscularis propria 4"
"N1c: tumour deposit(s) in the subserosa, mesentery, or non-peritonealised pericolic or perirectal tissues without regional nodal metastasis"
"Staging of rectal cancer uses the TNM staging system and strongly predicts the success rate and local recurrence following rectal cancer resection. MRI is the modality of choice for the staging of rectal cancer to guide surgical and non-surgical management options. MRI is used at diagnosis, following downstaging chemoradiotherapy, and in follow-up, if a non-operative approach is used."
"Note that there has been controversy regarding the ability of TNM 8 to appropriately identify high-risk factors in rectal cancer, most notably due to the emphasis placed on lymph node metastases, and not enough regard paid to tumour deposits 11."
"TNM staging"
"See TNM staging system for a general description, and terminology of rectal cancer staging lists the various abbreviations used in rectal cancer staging."
"Strictly speaking, TNM staging, such as the American Joint Committee on Cancer (AJCC) 8th edition, does not subclassify T3. However, this subclassification does have treatment and prognostic significance 7,8; tumours with a stage T3b or less confer a 5-year cancer-specific survival rate of 85%, whereas tumours with a stage T3c or greater have a 54% survival rate."
"Strictly speaking, TNM staging, such as the American Joint Committee on Cancer (AJCC) 8th edition, does not subclassify T3. However, this subclassification does have treatment and prognostic significance 7,8; tumours with a stage T3b or less confer a 5-year cancer-specific survival rate of 85%, whereas tumours with a stage T3c or greater have a 54% survival rate."
"The following are significant prognostic indicators, and should be commented on when staging rectal cancer with MRI, alongside the TNM stage:"
"Primary tumour staging (T)"
"Regional lymph nodes (N)"
"Metastases (M)"
"Tx: primary tumour cannot be assessed"
"Tis: carcinoma in situ: intraepithelial or invasion of lamina propria"
"T3a: tumour extends"
"T3b: tumour extends 1-5 mm beyond muscularis propria 4"
"T3c: tumour extends 5-15 mm beyond muscularis propria 4"
"T3d: tumour extends 15 mm beyond muscularis propria 4"
"T4a: tumour penetrates to the surface of the visceral peritoneum"
"T4b: tumour directly invades or is adherent to other organs or structures"
"Nx: regional nodes cannot be assessed"
"N1a: metastasis in 1 regional lymph node"
"N1b: metastasis in 2-3 regional lymph nodes"
"N1c: tumour deposit(s) in the subserosa, mesentery, or non-peritonealised pericolic or perirectal tissues without regional nodal metastasis"
"N2a: metastasis in 4-6 regional lymph nodes"
"N2b: metastasis in 7 or more regional lymph nodes"
"M1a: metastasis confined to one organ or site (for example, liver, lung, ovary, non-regional node) without peritoneal metastases"
"M1b: metastases in more than one organ"
"M1c: metastasis to the peritoneum with or without other organ involvement"
"T3 tumours may extend to or beyond the mesorectal fascia (MRF), which is highlighted with an additional prognostic descriptor T3 MRF+ 13"
"For cancers above the dentate line, regional nodes are mesorectal, superior rectal, inferior mesenteric, internal iliac and obturator. Common iliac, external iliac and inguinal nodes are not considered regional (except for tumours below the dentate line, when inguinal nodes are considered regional). Size is not considered to be a very helpful criterion; up to 40% of nodes 9 mm in short axis diameter are considered suspicious. If between 5 and 9 mm, they must have two of three characteristics listed above: signal heterogeneity, irregular contour or round shape. If 5 mm are considered to remain involved."
"For cancers above the dentate line, regional nodes are mesorectal, superior rectal, inferior mesenteric, internal iliac and obturator. Common iliac, external iliac and inguinal nodes are not considered regional (except for tumours below the dentate line, when inguinal nodes are considered regional). Size is not considered to be a very helpful criterion; up to 40% of nodes 9 mm in short axis diameter are considered suspicious. If between 5 and 9 mm, they must have two of three characteristics listed above: signal heterogeneity, irregular contour or round shape. If 5 mm are considered to remain involved."
Expected headings
"TNM staging"
"Primary tumour staging (T)"
"Regional lymph nodes (N)"
"Metastases (M)"
"Stage groupings"
"Additional prognostic indicators"
"Additional specific MRI imaging staging subsets of rectal tumour"
"Strictly speaking, TNM staging, such as the American Joint Committee on Cancer (AJCC) 8th edition, does not subclassify T3. However, this subclassification does have treatment and prognostic significance 7,8; tumours with a stage T3b or less confer a 5-year cancer-specific survival rate of 85%, whereas tumours with a stage T3c or greater have a 54% survival rate."
"When assessing T3 disease, it is important to remember that desmoplastic reaction can mimic this due to fibrosis; however, desmoplastic reaction has a spiky and sharp configuration, whereas tumour usually has a nodular and lumpy configuration."
"The planes that the small field-of-view axial and coronal sequences have been acquired in should be carefully scrutinised; obliquity may lead to overstaging of tumours due to apparent transgression of tumour through the muscularis propria, but that is in fact an artifact of the plane and volume averaging."
"For cancers above the dentate line, regional nodes are mesorectal, superior rectal, inferior mesenteric, internal iliac and obturator. Common iliac, external iliac and inguinal nodes are not considered regional (except for tumours below the dentate line, when inguinal nodes are considered regional). Size is not considered to be a very helpful criterion; up to 40% of nodes 9 mm in short axis diameter are considered suspicious. If between 5 and 9 mm, they must have two of three characteristics listed above: signal heterogeneity, irregular contour or round shape. If 5 mm are considered to remain involved."