Table 1.

Summary of TNM guidelines for the staging of prostate cancer

Category	Definition
Tumour
Tx	Primary tumour cannot be assessed (e.g. CT study, severe artefacts on MRI)
T1a–T1b	Tumour incidental histologic finding
T1c	Tumour identified by needle biopsy but not visible by imaging
T2	Organ confined disease
T2a	The tumour involves up to one half of 1 side of the prostate
T2b	The tumour involves more than one half of 1 side of the prostate
T2c	The tumour involves both sides of the prostate
T3	Extraprostatic extension
T3a	Extraprostatic extension (unilateral or bilateral) or microscopic invasion of the bladder neck
T3b	Tumour invades seminal vesicle(s)
T4	Tumour invades adjacent structures other than seminal vesicles, such as external sphincter, rectum, bladder, levator muscles, and/or pelvic wall
Node
Nx	Regional lymph nodes were not assessed
N0	No positive regional lymph nodes
N1	Metastases in regional lymph node(s)
Metastasis
Mx	M staging not assessed (e.g. MRI with pelvic only coverage)
M0	No distant metastasis
M1	Distant metastasis
M1a	Nonregional lymph node(s)
M1b	Bones
M1c	Other site(s) with or without bone disease