Diagnosis
Although the DRE and PSA tests cannot diagnose prostate cancer, they can signal the need for a biopsy to examine the prostate cells and determine whether they are cancerous. In some men, changes in urinary or sexual function lead to a full evaluation by the doctor, and, if prostate cancer is suspected, a biopsy will be performed.

The Biopsy
During a biopsy, needles are inserted into the prostate to take small samples of tissue, often under the guidance of ultrasound imaging. The biopsy procedure may cause some discomfort or pain, but the procedure is short, and can usually be performed without an overnight hospital stay.

Gleason Grading and Gleason Scores
Under normal conditions, prostate cells, just like all other cells in the body, are constantly reproducing and dying, and each new prostate cell has the same shape and appearance as all of the other prostate cells. But cancer cells look different, and the degree to which they look different from normal cells is what determines the cancer grade. “Low-grade” tumor cells tend to look very similar to normal cells, whereas “high-grade” tumor cells have mutated so much that they often barely resemble the normal cells.

The Gleason grading system accounts for the five distinct patterns that prostate tumor cells tend to go through as they change from normal cells. The scale runs from 1 to 5, where 1 represents cells that are very nearly normal, and 5 represents cells that don’t look much like prostate cells at all.

After examining the cells under a microscope, the pathologist looking at the biopsy sample assigns one Gleason grade to the most common pattern, and a second Gleason grade to the next most common pattern. The two grades are added, and the Gleason score, or sum, is determined.

Generally speaking, the Gleason score tends to predict the aggressiveness of the disease and how it will behave. The higher the Gleason score, the less the cells behave like normal cells, and the more aggressive the tumor tends to be.