Because prostate cancer often has no symptoms, urologists and other physicians rely on two common tests to screen for the disease. These tests may be combined for increased accuracy. Although these tests cannot prove the existence of prostate cancer, they can indicate the need for further assessment. These screening tests are:

• Digital rectal exam (DRE). The physician gently inserts a gloved, lubricated finger a few inches into the rectum and presses against the prostate to feel for nodules, hardness or other irregularities. The patient stands bent over a table or lies sideways with his knees against his chest. Most men find the DRE uncomfortable but not painful.
  
  
• Prostate-specific antigen (PSA) test. This blood test checks for PSA, a protein made in the prostate and found in the blood.  A sample of blood is drawn from the arm. Prostate cancer often raises the PSA level in blood above the normal 4 nanograms per milliliter (ng/mL). Infection, an enlarged prostate and other factors can affect PSA levels. According to the American Cancer Society (ACS):
  
  
• PSA of 4 to 10 ng/mL shows a 25 percent chance of having prostate cancer.
  
  
• PSA of more than 10 shows a 50 percent chance of having prostate cancer, with the risk rising as the PSA level grows.
  
  
Changes in the PSA, which should be tested at regular intervals, may be as significant as the absolute level. Some studies show that the changes in PSA, or PSA velocity, may provide keys to those prostate cancers that are more likely to be aggressive and require treatment.

Physicians differ on when to make the DRE and PSA test part of a man’s regular interval physical examination. Often these assessments are started around age 50 but may begin earlier for higher-risk men, such as black men or men who have a brother, father or son with prostate cancer. The DRE is less effective than the PSA in detecting prostate cancer, but in some cases it may find prostate cancer in men with low PSA levels. DRE can sometimes detect anatomic evidence for prostate cancer, which reinforces the ACS recommendation that both the DRE and PSA be used for screening. The PSA screening may not benefit men over age 75. At that age, treating a slow growing cancer may not improve a man’s life expectancy.

Depending on the results of these tests, the physician may order additional procedures:

• Transrectal ultrasound (TRUS). An ultrasound machine uses harmless sound waves to create pictures of the prostate on a video monitor. The physician picks up the sound waves through a small probe placed into the rectum. Insertion of the probe may be uncomfortable, but TRUS lasts only a few minutes.
  
  
• Biopsy. A sample of suspected tissue is taken for examination under a microscope. The most common method is core needle biopsy. Using ultrasound as a guide, the physician places a needle through the rectum into the prostate gland to extract cells. Pain is typically minimal because the procedure is performed quickly and a local anesthetic may be used. A biopsy is the definitive way to determine the type and grade of the cancer. 
  
  If biopsy detects high-grade prostatic intraepithelial neoplasia (PIN), an abnormal microscopic finding, there is a 30 to 50 percent chance of prostate cancer, according to the ACS. Men with high-level PIN are thus monitored closely and may undergo regular biopsies.

If prostate cancer is diagnosed, CAT scan, ultrasound, MRI or bone scan may be used to assess its size and track any spread to other areas. Another method to assess whether prostate cancer has metastasized is pelvic lymph node dissection, which is the surgical removal and microscopic inspection of nearby lymph nodes. This procedure may involve open surgery or laparoscopic surgery through a small incision in the abdomen. It is important to determine if, and how far, the cancer has spread because this information will influence the treatment plan and the patient's prognosis (outlook for recovery).