Table 1.

The preoperative TNM staging standards in current study

TNM staging	MSCT (cTNM)	TRUS (uTNM)
T stage
0	No detectable enhanced lesion in pelvis	No invasive-lesion detected
T1	Intraluminal polypoid neoplasm, without enhancement of bowel wall	Invasive lesion with mucosal and submucosal confinement
T2	Partial enhancement of bowel wall near the detectable mass	Lesion confined to the muscularis propria Invasion of the second hypoechogenic layer
T3	Thickening of bowel wall (more than 0.5cm), without invasion of surrounding structures	Lesion penetrating all rectal layers Invasion of the perirectal fat, without pelvic organ invasion
T4	Invasion of surrounding tissue (prostate, vagina, uterus, cervix, bladder, etc.)	Invasion of pelvic organ (prostate, vagina, uterus, cervix, bladder, etc.)
N stage
N0	No visible lymph node	Undetectable adenopathy
N1	Up to three lymph nodes (diameter ≥8mm) with distributed enhancement	Up to three detectable tumor lymph nodes with circular hypoechoic structures (diameter≥3mm)
N2	More than three detectable lymph nodes (diameter ≥8mm), with distributed enhancement	More than three detectable tumor lymph nodes with circular hypoechoic structures (diameter≥3mm)
M stage
M0	No distant metastases	Not available
M1	Distant metastases (omentum, peritoneum, liver, bone, etc.)	Not available

The cTNM stands for clinical tumor stage evaluated on basis of MSCT, with the uTNM for ultrasonographic stage evaluated by TRUS. Abbreviations: MSCT, multi-slice spiral computed tomography; TRUS, transrectal ultrasound.