PROSTATE CANCER STAGING

Prostate cancer staging
Tumour staging uses the TNM classification. As with all cancer, prostate cancer staging may be considered clinical (prefixed with c) or pathological (prefixed with p), dependent on available data.

T stage
is assessed by digital rectal examination and imaging (TRUS, MRI). Current imaging resolution limits reliability in detection of focal and microscopic extraprostatic extension of disease. Recent prostatic biopsy may also confuse the interpretation of MRI images, particularly regarding the seminal vesicles.

N stage
is assessed by imaging (MRI) or biopsy as necessary. Pelvic lymph node dissection is the gold-standard assessment of N stage. MRI or CT scanning may image enlarged nodes and most radiologists report nodes of >8mm in maximal diameter. However, nodes larger than this often contain no cancer, while micrometastases may be present in normal-sized nodes.

M stage
is assessed by physical examination, imaging (MRI or isotope bone scan, chest radiology) and biochemical investigations (including creatinine and alkaline phosphatase).

Partin's nomograms
based on several thousand radical prostatectomies, are used widely to predict pathological T and N stage by combining clinical T stage, PSA, and biopsy Gleason score. Higher pathological stage (i.e. pT3 disease) found at radical prostatectomy may also be predicted by:
- higher percentages (>66%) of positive biopsies
- cancer invading adipose in the biopsies (there is no fat in the prostate)
- possibly the presence of perineural cancer invasion within the prostate.