The gold standard for diagnosing prostate cancer is the prostate biopsy, collecting small samples of prostate tissue and identifying abnormal cells under the microscope. If cancer is found, the doctor will use the sample and imaging tests, such as an ultrasound, to determine the cancer's stage (how far it has spread into the body) and grade (how abnormal the cells appear). The more abnormal the tumor cells are, the more likely it is that the cancer will be aggressive.
The total PSA (total prostate specific antigen) blood test and digital rectal exam (DRE) are the primary tools used to help determine the need for a prostate biopsy. The DRE is a physical examination. To perform the DRE test, the doctor inserts a gloved, lubricated finger into the rectum and feels the prostate gland with his finger to detect abnormalities.
Laboratory testing is used to screen asymptomatic and symptomatic men for cancer, rule out other diseases and conditions that may be causing or exacerbating a person's symptoms, monitor the effectiveness of treatment for cancer, and monitor for recurrence.
Testing may include:
- PSA (total prostate specific antigen) – to help screen for and monitor prostate cancer. PSA is a good but not perfect tool. There is currently no consensus on the routine use of the PSA test to screen asymptomatic men. Some national organizations such as the American Urological Association recommend screening, while others such as the U.S. Preventive Services Task Force feel that the harms associated with over-diagnosis and over-treatment outweigh the potential benefits. (See Screening Tests for Adults (30-49): Prostate cancer and Screening Tests for Adults (50 and Up): Prostate cancer for details on screening recommendations.) Increased levels of PSA have been associated with an increased risk of prostate cancer but are also found with BPH, prostatitis, infection, and a variety of other temporary conditions. About two-thirds of men with an abnormal PSA level do not have prostate cancer, and about 20% of those with prostate cancer will have normal PSA concentrations. When evaluating the results, the doctor must consider both the concentration of PSA in the blood and the volume of the man's prostate. (See the PSA test page for discussion of variations of the PSA test.)
- Urinalysis – to screen for kidney disorders and urinary tract infection (UTI)
- Urine Culture – to look for signs of a UTI
- Blood Urea Nitrogen (BUN) and Creatinine – blood tests to evaluate kidney function
Non-laboratory tests may include:
- Ultrasound – a transrectal ultrasound (TRUS) may be used to help measure the size of the prostate and to help guide needle placement during a prostate biopsy
- CT (computed tomography) – to help evaluate the extent of the cancer
- MRI (magnetic resonance imaging) – to help evaluate the extent of the cancer
- Radionuclide bone scintigraphy – occasionally used to detect cancer that has spread to bone
- PET (positronic emission tomography) – occasionally used to help stage metastatic cancer (cancer that has spread beyond the prostate)