Clinical Definition

The Gleason score is a system used to classify adenocarcinoma of the prostate. A tissue sample is evaluated to determine glandular differentiation. A Gleason score may range from 2 to 10 based on the pattern of the tissue sample. A lower number indicates the tissue has a structure closer to normal prostate tissue. The higher the score, the more abnormal the tissue looks, which often indicates a more aggressive carcinoma.

In Our Own Words

The Gleason score is a system used to grade prostate cancer. Cancer grading is one of several pieces of information doctors use to evaluate the severity of the cancer, which may help guide treatment decisions. In order to determine a Gleason Score, samples of cancerous cells from the prostate are taken during a biopsy and viewed under a microscope.

The doctor who scores the samples always tries to take two areas or patterns of cells and then scores each one and adds them together. For example, if both areas score a 1, then the Gleason score is (1 + 1) = 2. So, the Gleason score ranges from 2 to 10 depending on the scores of each sample area.

In general, a lower score means the cancer looks similar to normal tissue and is less likely to spread. Higher Gleason scores indicate the cancer is more likely to be aggressive and spread. Prostate cancer is very complicated, though, and this general rule does not always apply for an individual