A Gleason score of 6 indicates a low-grade or less aggressive form of prostate cancer, states the American Cancer Society. It is the lowest score given to cancer found on a prostate biopsy. These cancers tend to spread slowly compared to other prostate cancers.
When doctors conduct a prostate biopsy, they usually take samples from the two areas that make up the bulk of the cancer and assign each of them a grade of 1 to 5, states the American Cancer Society. A 1 indicates that the cancer tissue appears like normal prostate tissue, while a 5 indicates highly abnormal cancer cells and growth patterns. The sum of these scores is the Gleason score.
The Gleason score is an important indicator of the aggressiveness of the cancer; however, doctors also use other factors to predict the behavior of prostate cancer, advises the American Cancer Society. These factors include results from a rectal examination and the amount of each biopsy sample that contained cancer. Doctors also consider how much the cancer has already spread and whether it is found on both sides of the prostate.
The PSA, or prostate-specific antigen, test, is another screening test for prostate cancer, advises WebMD. If the PSA levels are elevated, there is a greater chance the patient has cancer.