Prostate cancer staging

Your treatment options for prostate cancer will be affected by the type of cancer cells in your prostate and whether it has spread beyond your prostate. After you’ve had a biopsy, and before recommending treatment, your doctor will work out the stage or extent of the cancer.

The stage is based on several factors:

  • the result of your PSA test
  • the result of your biopsy
  • how aggressive the cancer is (grading or your cancer score)
  • how far it has spread (your TNM score).

PSA test

A high prostate specific antigen (PSA) reading is a sign that you could have prostate cancer. Only 1 in 3 men with a high reading has prostate cancer. Also, a high PSA result doesn’t tell whether your cancer is very slow growing (and unlikely to cause harm), or whether it’s likely to spread rapidly. So your doctor will offer you a biopsy to give a better idea of the type, aggressiveness and spread of your cancer.

Biopsy and grading

The biopsy will enable your doctor to identify the type of cancer cells in your prostate. They are graded depending on how different they look from normal tissue. Cells that are not that different from normal tissue are unlikely to grow as aggressively as cells that look very different. Your doctor will grade the cells between 1 (least aggressive) and 5 (most aggressive). The pathologist will then add the grade of the two most common types of cells together to give you a score (e.g. 3+4=7)

Staging with the Tumour-Node-Metastasis (TNM) system

The TNM system is a way to assess the size of the cancer and how far it has spread. It answers 3 questions:

  • Where is the tumour? Is it inside the prostate, or has it spread to nearby structures? Your doctor will assess this by a digital rectal examination and/or an MRI scan.
  • Is there cancer in the nearby lymph nodes? Your doctor will order a CT or MRI scan to assess this.
  • Has it metastasised? A bone scan or a prostate specific membrane antigen (PSMA) scan can determine whether the cancer has spread to other parts of your body, including your bones.

The results of the grading and staging are then combined to give a clear idea of your best options for treatment.