Testing a blood sample for the level of Prostate Specific Antigen (PSA) plays an important part in the early detection of prostate cancer. PSA is a substance made by the normal prostate gland. Although PSA is mostly found in semen, a small amount is also present in the blood. 

Most men have levels under four micrograms per litre (ug/L) of blood. There are more valid age-adjusted normal ranges also used. When prostate cancer develops, the PSA level usually goes above 4 (or the age-adjusted level); however, a high PSA score does not always indicate cancer.

Although a digital rectal exam (DRE) is less effective than the PSA blood test in finding prostate cancer, this exam can sometimes detect cancers in men with normal PSA levels. For this reason, most cancer and urological organisation guidelines recommend the use of both a DRE and a PSA blood test for early prostate cancer detection.

When a doctor suspects prostate cancer, based on the results of a DRE and / or PSA, the diagnosis must be confirmed by doing a biopsy.

Recently, MRI has also been adopted in determining who should be investigated further. Approximately 80% of significant cancers can be detected on MRI. MRI is less effective at detecting low-grade prostate cancer. MRI often underestimates the volume of prostate cancer (when compared to the volume of prostate cancer present in the prostate as determined by the pathologist after the prostate removal). There are small risks of false-positive findings with MRI scans.

A prostate biopsy is required to confirm or refute the clinical findings. Traditionally prostate biopsies have been done as a TRUS (Transrectal ultrasound guided) biopsy. (i.e. through the rectum). There is now the option of performing a Transperineal ultrasound guided prostate biopsy (i.e. through the skin below the scrotum). Either option is valid.

Transrectal biopsy has the advantage of being done as an office procedure under local anaesthetic.

Transperineal biopsy has the advantage of more thorough sampling of the anterior (front) part of the prostate, which is particularly important if an MRI has detected a suspicious lesion in this location. This is done under general anaesthetic in hospital. In addition there is no risk of serious infection with the Transperineal approach (1-2% with the Transrectal biopsy).

Recently a new development in Radiological staging is the arrival of PSMA PET CT scanning. This scan is more specific and sensitive than CT and bone scanning, and is becoming the staging modality of choice in excluding metastatic disease, or re-staging men with rising PSA whose treatment is no longer working.