PSA blood test and Digital Rectal Exam (DRE) can be used to detect prostate cancer.
Although a high PSA may increase a doctor’s suspicion of prostate cancer, a biopsy is almost always done to confirm a diagnosis
Disclaimer: This information isn’t a substitute for professional medical advice, diagnosis, or treatment. You should never rely upon this article for specific medical advice. If you have any questions or concerns, please talk to your doctor.
Detecting Prostate Cancer
The PSA blood test and Digital Rectal Exam (DRE) can be used to detect prostate cancer when no symptoms are present. They can help catch the disease at an early stage when treatment is thought to be more effective and potentially has fewer side effects. It is recommended that you abstain from strenuous exercise and ejaculation for 48 hours preceding your PSA, since these may artificially inflate PSA test results.
After your PSA test, your health care provider may perform a DRE, in which a gloved, lubricated finger is inserted into the rectum to examine the prostate for any irregularities in size, shape, and texture.
During a PSA test, a small amount of blood is drawn from the arm, and the level of PSA, a protein produced by the prostate, is measured. The majority of men have a PSA under 1 ng/mL. Historically, many physicians used a PSA of 4 as the borderline between “normal” and “abnormal.” We now realize this question is more complicated.
Assessment of a “normal” PSA must take into account:
- The patient’s age
- Prostate size
- Previous PSA tests
- Other medical conditions, such as BPH or prostatitis
- Drugs that may artificially lower PSA, such as finasteride (Proscar® or Propecia®) or dutasteride (Avodart®)
- Infections and procedures involving the urinary tract that can elevate the PSA
- Use of various herbal supplements, such as saw palmetto
Making the Diagnosis via Biopsy
Although a high PSA may increase a doctor’s suspicion of prostate cancer, a biopsy is almost always done to confirm a diagnosis. A PSA test is simply used to assess whether or not you should have further testing—usually in the form of a prostate cancer biopsy to determine the presence of cancer cells.
There are 3 main ways men are initially diagnosed:
- TRUS-guided biopsy: A Trans-Rectal Ultra- Sound-guided biopsy using local anesthetic is the most common way that prostate cancer is diagnosed in the US. An ultrasound probe is placed in the rectum to allow visualization of the prostate, then multiple needles are used to sample for cancer. If a patient had magnetic resonance imaging (MRI) before the biopsy, needles may be targeted into areas that looked suspicious on the MRI (the MRI itself provides useful information,
but cannot diagnose prostate cancer).
- Trans-perineal biopsy: The prostate can also be biopsied under local anesthetic by placing a needle through the skin between the scrotum and anus (perineum).
- Incidentally: Some men are diagnosed when prostate cancer is found incidentally during an unrelated surgical procedure of the prostate or bladder.
Prostate tissue from the biopsy is then examined under a microscope by a pathologist to confirm the presence or absence of prostate cancer cells.
“Targeted” or “fusion” biopsies (sometimes referred to as an MRI fusion biopsy) are increasingly being offered at select centers that use MRI, in addition to the ultrasound, to better visualize tumors within the prostate and help guide biopsy needles to the most concerning areas. There is wide variation in quality of MRI; at this point in time, MRI and fusion biopsy should only be performed at a high-volume center with particular expertise in prostate radiology. Research on the continued improvement of this technology continues.
To learn more, please visit the Prostate Cancer Foundation at PCF.org.