Prostate Cancer - Detection & Diagnosis

Detection & Diagnosis

Digital Rectal Exam (DRE)
The simplest and oldest screening test for prostate cancer is the digital rectal exam, or DRE. The urologist gently inserts a gloved forefinger into the rectum in order to feel the prostate gland for enlargement or other obvious abnormalities, such as a lump. Of course, the DRE is not a definitive cancer test, but regular exams help the urologist detect any changes in the prostate over time that might signal pre-cancerous conditions. DREs are recommended as part of a man's annual physical exam beginning at age 50.

PSA Test
Prostate-specific antigen (PSA) is a glycoprotein produced by the epithelial cells of the prostate gland. A blood test measures the amount of PSA circulating in the blood, expressed in nanograms per milliliter (ng/mL). The resulting PSA level is used to assess cancer risk:

PSA Level	Probability of Cancer
0-2 ng/mL	1%
2-4 ng/mL	15%
4-10 ng/mL	25%
>10 ng/mL	>50%

However, there is no simple correlation between PSA level and disease stage, and elevated PSA can also indicate non-cancerous conditions such as infection or benign prostatic hyperplasia (enlarged prostate). Additionally, low PSA levels don't always mean there's no cancer. PSA is not specific to cancer, but rather to prostate tissue.

Despite its limitations, PSA testing has helped detect cancer in countless individuals. In 1984, before PSA testing was available, the chance of finding localized prostate cancer was about 50%, either incidentally or during other procedures. In 1993, after PSA testing became widely used, that figure jumped to over 90%.

As with all cancers, early detection is the best hope for a cure. Routine PSA screening is recommended starting at age 50 for Caucasian men, and age 45 for African-American men or others at high risk for prostate cancer.

Researchers at M. D. Anderson are searching for new "markers" that correlate to tumors rather than prostate tissue, with the ultimate goal of a more accurate prostate cancer screening tool.

Prostate Biopsy
A biopsy, or sampling of prostate tissue, is currently the only definitive method of diagnosing prostate cancer. A biopsy is performed on all men with a strong suspicion of cancer based on PSA test results and other factors.

A biopsy takes about 35 minutes to perform and is done as an outpatient procedure. Biopsies are generally well-tolerated with minimal pain and bleeding. Before the biopsy, the patient undergoes an enema and is given an antibiotic. Lidocaine is used to deaden the nerves that lie alongside the prostate gland to make the procedure more comfortable.

A transrectal ultrasound (TRUS) probe is inserted into the rectum so the oncologist can view the prostate, which takes about 10 minutes. Then, a fine-gauge, spring-loaded biopsy needle is used to remove six to 10 tiny "core" samples of tissue from specific, predetermined areas on the prostate gland. The biopsy specimens take about three to seven days to process.

Gleason Grading System
Prostate cancers contain several types of cells that appear differently under a microscope. The Gleason grading system uses the numbers 1- 5 to "grade" the most common (primary) and next most common (secondary) cell types found in a tissue sample. Together, the sum of these two numbers is the Gleason score, ranging from 2-10 at M. D. Anderson, and tells the physician how aggressive the tumor appears under the microscope. The higher the Gleason score, the more aggressive the cancer. The Gleason score is considered along with other factors to help select the most appropriate treatment for the patient.