How is prostate cancer diagnosed?
A number of tests may be performed to investigate symptoms of prostate cancer and confirm a diagnosis. Some of the more common tests include:
- physical examination and medical history
- digital rectal examination – where the doctor inserts a gloved finger into your rectum to feel the prostate through the rectal wall
- blood test to check for prostate-specific antigen (PSA), a protein produced by the prostate. The level of PSA can be higher than normal in people with prostate cancer (but also in people with other prostate conditions that are not cancer)
- transrectal ultrasound – where a probe is inserted into the rectum that uses sound waves to create a picture of the prostate inside the body
- magnetic resonance imaging (MRI), a type of medical scan
- biopsy – where a small sample of tissue is removed to be examined under a microscope. The biopsy results include a Gleason score – a score from 2 to 10 used by the pathologist that indicates the likelihood of the tumour spreading outside the prostate (2 is least likely to spread, and 10 is most likely to spread).
If you are diagnosed with prostate cancer, you might have more tests to determine the stage of the disease and whether the cancer has spread to other parts of the body. Knowing the stage of the disease helps your medical team plan the best treatment for you.
Prostate cancer is staged using the following information:
- size and extent of the tumour
- whether the cancer has spread to nearby lymph nodes
- whether the cancer has spread to other organs or tissues in the body
- PSA level at diagnosis
- Gleason score from the prostate biopsy.
Stages of prostate cancer are:
- Stage I: the tumour has not spread outside the prostate. The tumour is small and may or may not be able to be felt during a digital rectal exam or seen with medical imaging tests. If it can be seen in tests, the tumour is in half or less of the prostate and on 1 side only. The Gleason score is 6 or less and the PSA level is less than 10.
- Stage IIA: the tumour has not spread outside the prostate. The Gleason score can be 6 or lower but the PSA level is between 10 and 20, or the Gleason score can be 7 and the PSA level is less than 20. The tumour may be in more than half of the prostate.
- Stage IIB: the tumour has not spread outside the prostate. The tumour is small and may not be felt during a digital rectal exam or seen with medical imaging tests, but the Gleason score is 8 or higher or the PSA level is 20 or higher. If the tumour can be seen with medical imaging tests, it is in both sides of the prostate.
- Stage III: the tumour has spread beyond the outer layer of the prostate and may have spread to the seminal vesicles, but not to nearby lymph nodes. The PSA level and Gleason score can be any numbers.
- Stage IV: the cancer has spread to nearby tissues such as the seminal vesicles, rectum or bladder, to nearby lymph nodes, or to distant parts of the body such as the bones. The PSA level and Gleason score can be any numbers.
Tests to determine the stage of prostate cancer can include:
- transrectal ultrasound
- biopsy or removal of lymph nodes – where tissue from the lymph nodes is taken to be examined under a microscope
- bone scan
- CT, MRI or other scans.
National Cancer Institute (2014). Prostate cancer treatment (PDQ®) http://www.cancer.gov/cancertopics/pdq/treatment/prostate/Patient, patient version.
American Cancer Society (2015). Prostate cancer http://www.cancer.org/Cancer/ProstateCancer/DetailedGuide/index.