The best way to diagnose prostate cancer involves a digital rectal exam and a prostate specific antigen (PSA) blood test. Patients with localized cancer rarely have any symptoms. New markers for the early detection of prostate cancer are under development and study.
Digital Rectal Exam
The Digital Rectal Examination (DRE) may detect a cancer and judge whether it is confined to the prostate. The Prostate lies in front of the rectum; therefore, the doctor can feel the prostate by inserting a gloved, lubricated finger into the rectum. The DRE is not always accurate, as many prostate cancers are situated deeper in the gland or are too small for detection, and not all ‘lumps’ on the prostate are cancerous. Once a cancer can be felt as a lump, it is considered to be at a more advanced stage than when it is detected only by a PSA blood test.
Prostate-Specific Antigen (PSA)
Prostate-specific antigen (PSA) is a protein produced by both normal and cancerous prostate cells. When prostate cancer grows or when other prostate diseases are present, the amount of PSA in the blood may increase.
A PSA test is generally said to be in the normal range when it is reported to be between 0 and 2.5 nanograms per milliliter (sometimes abbreviated as ng/mL on the lab report) and not increasing over time. PSA may be elevated because of a non-cancerous condition, such as enlargement or inflammation of the prostate.
If the results are in the high range (or have increased since a prior test), your physician may suggest a biopsy, which is the only test to actually diagnose prostate cancer.
Percent-Free PSA Ratio
Percent-free PSA ratio is a blood test that measures how much PSA circulates by itself (unbound) in the blood, and how much is bound together with other blood proteins. If PSA results are elevated and percent-free PSA ratio is low (10% or less), then prostate cancer is more likely to be present. If this is the case, a biopsy may be needed.
Transrectal ultrasonography (TRUS) is the most direct way to see the prostate gland. Ultrasound provides an image that can be used to measure the size of the prostate and sometimes can detect suspicious tissue. TRUS is almost always done in combination with a biopsy. When a needle biopsy of the prostate is performed, it is always done under ultrasound guidance.
A prostate biopsy removes small amounts of tissue to examine under a microscope to determine whether cancer is present. Typically between 6 and 12 biopsies are taken from the prostate using a core biopsy needle. By examining tissue samples under a microscope, the diagnosis of cancer can be established. When a tumor is discovered, it is classified, under the microscope, into a category called tumor ‘grade’.
Last update: September 14, 2020