Prostate cancer is diagnosed through a range of tests. These include measuring serum prostate-specific antigen (PSA) levels, digital rectal examination, rectal ultrasound, imaging tests such as MRI or CT scans and prostate biopsy. Biopsy specimens are scored based on the appearance of the prostate cells under a microscope. This is a form of tumour grading which gives an indication of the abnormality of the prostate cells. The most common system used is the Gleason score. This is used to help predict disease outcome; cancers with higher Gleason scores are more aggressive and are associated with worse prognoses. Tumours are also staged to determine how far the cancer has spread, most commonly using the TNM (tumour, node, metastasis) system.

Based on the results of these tests, people with prostate cancer are categorised into 1 of 3 risk groups (often called D'Amico risk classification). The criteria for the different risk groups are outlined in NICE's guideline on prostate cancer: diagnosis and treatment, and the classification is used to help guide treatment decisions. The groups are as follows:

  • Low risk: PSA score of less than 10 ng/ml, and small size tumour confined within the prostate (T1–T2a), and biopsy result showing a Gleason score of less than 6.

  • Intermediate risk: PSA score of 10–20 ng/ml, or tumour confined to the prostate involving more than 50% of 1 lobe (T2b), or biopsy results showing a Gleason score of 7.

  • High risk: PSA score of more than 20 ng/ml, or tumour confined to the prostate involving both lobes (T2c and above), or biopsy results showing a Gleason score of 8–10.

Clinicians can also use nomograms (mathematical models) to help make decisions about treatment. A nomogram predicts long-term outcomes in people with prostate cancer. Nomograms can use various factors including TNM, PSA level and Gleason score to estimate the risk of the cancer spreading to other parts of the body or recurrence after treatment (surgery or radiotherapy).

Depending on their risk group, people with prostate cancer may be offered the following options:

  • Watchful waiting, where no treatment is given, but patients are monitored for signs of change. If symptoms of progressive disease are found, treatment aims to control the cancer rather than cure it.

  • Active surveillance, where no treatment is given, but patients are closely monitored for signs of change. If any changes are found, treatment aims to cure the cancer.

  • Radical prostatectomy (surgical removal of the prostate) with or without removal of lymph nodes.

  • External beam radiotherapy with or without brachytherapy (internal radiotherapy).

  • Brachytherapy alone.

  • Hormonal therapy.

For many people prostate cancer can be cured with surgery or radiotherapy, but in around 1 in 3 cases the cancer comes back some time after treatment. PSA levels are used to monitor this. An increase in the levels of PSA is called biochemical recurrence and may indicate that further treatment is needed (Cancer Research UK 2014d).

Despite the routine use of risk classification and nomograms to categorise prostate cancer, these tools have some limitations. These include the lack of patient specificity, which may lead to misclassifications and to over- or under-treatment. A more personalised approach for assigning risk categories to people diagnosed with prostate cancer may improve accuracy and, therefore, appropriateness of treatment.