Copyright ©The Author(s) 2015.
World J Gastroenterol. Jul 7, 2015; 21(25): 7659-7671
Published online Jul 7, 2015. doi: 10.3748/wjg.v21.i25.7659
Table 1 Strengths of preoperative imaging studies for rectal cancer
CRMT stageN stageEMVIPeritoneum
Table 2 Tumor-node-metastasis staging system for rectal cancer (reproduced with permission from Greene et al[33])
Primary tumor (T)
TxPrimary tumor cannot be assessed
T0No evidence of primary tumor
TisCarcinoma in situ: intraepithelial or invasion of lamina propria
T1Tumor invades submucosa
T2Tumor invades muscularis propria
T3Tumor invades through the muscularis propria into the pericolorectal tissues
T4aTumor penetrates to the surface of the visceral peritoneum
T4bTumor directly invades or is adherent to other organs or structures
Regional lymph nodes (N)
NXRegional lymph nodes cannot be assessed
N0No regional lymph node metastasis
N1Metastasis in 1-3 regional lymph nodes
N1aMetastasis in one regional lymph node
N1bMetastasis in 2-3 regional lymph nodes
N1cTumor deposit(s) in the subserosa, mesentery, or nonperitonealized pericolonic or perirectal tissues without without regional node metastasis
N2Metastasis in four or more regional lymph nodes
N2aMetastasis in 4-6 regional lymph nodes
N2bMetastasis in seven or more regional lymph nodes
Distant metastasis (M)
M0No distant metastasis
M1Distant metastasis
M1aMetastasis confined to one organ or site (e.g., liver, lung, ovary, nonregional node)
M1bMetastasis in more than one organ/site or the peritoneum
Table 3 Vocabulary for the treatment of rectal cancer
Anterior resectionResection of rectum with an anastomosis above the pelvic peritoneal reflection
Low anterior resectionResection of rectum with an anastomosis below the pelvic peritoneal reflection
TMETotal mesorectal resection. The adipose tissue at the posterior and lateral aspects of the rectum which contains the draining lymph nodes, is dissected down to the pelvic floor and resected
PMEPartial mesorectal excision. The mesorectum is divided 5 cm below the cancer as well as the distal rectum. PME is performed for cancers located in the upper rectum and rectosigmoid junction
TEMTransanal endoscopic microsurgery. A specially designed proctoscope with an attached microscope permits local resection of premalignant lesions and selected cases of early rectal cancer up to 20 cm from the anal verge
TAETransanal excision. Lesions in the lower third of rectum can be resected transanally
APRAbdominoperineal resection. Low rectal cancers that cannot be resected with a sphincter-saving procedure are resected with perianal tissue and the anal canal en bloc with the whole rectum and mesorectum
AdjuvantAdditional treatment (chemotherapy, radiation therapy or chemoradiation) given after surgical resection
NeoadjuvantPreoperative treatment
CRTChemoradiotherapy. Chemotherapy drugs typically involve 5-fluorouracil, leucovorin and oxaliplatin. These are given in order to increase cancer cells sensitivity to the radiation. CRT is frequently offered to patients preoperatively (neoadjuvant) in order to reduce local recurrence but has not shown to improve overall survival
Intersphincteric resectionThe internal anal sphincter muscle is resected in continuity with the lower rectum preserving the external anal sphincter in order to preserve anal function and avoid colostomy in cases of ultralow rectal cancer
CRMCircumferential resection margin is the distance in mm from the mesorectal fascia (the resection plane) to the nearest tumor growth
DRMDistal resection margin
Table 4 Morphologic features of favorable and unfavorable T1 rectal cancers
Favorable/low riskUnfavorable/high risk
Well differentiated (G1-G2)Poorly differentiated (G3)
SM 1SM 2-3
Size < 3 cmSize > 3 cm
< 40% wall circumferences> 40% wall circumferences
No lymphovascular invasionLymphovascular invasion
No tumor buddingTumor budding
No perineural invasionPerineural invasion
No lymphocitic infiltrationLymphocitic infiltration