Larry Bans: PSA is simply a measurement of this protein called prostate specific antigen that spills or seeps out into the bloodstream from the prostate cells. The higher the level of PSA, the more likely the malignancy may be present, but it’s not an all or none phenomenon. So PSA can be used as a screening test in a sense that if it’s high, we worry that there might be underlying prostate cancer, but there are other reasons for PSAs to be abnormally elevated, and those reasons can include just benign enlargement of the prostate, they can include inflammation or infection of the prostate, sometimes prostatitis, or an infection in the prostate can raise a PSA. So it’s important to realize that an elevated PSA may be a potential sign that cancer is present but it doesn’t absolutely mean that. Gleason grading is determined by the pathologist who looks at the biopsy material or the prostatectomy specimen, and that pathologist assigns these two numbers, the Gleason scores, to the tissue that he or she examines under the microscope. The prognostic implication is that people with lower Gleason scores, likely have less aggressive or slower growing cancers, people with the high scores have more aggressive or potentially more serious cancers. The most common form by and far today is a three plus three pattern, which is usually a relatively slow growing malignancy. If people have element of Gleason four or five in their prostate cancer specimen, it’s a more serious disease and potentially can spread quicker.