If you are diagnosed with prostate cancer, your doctor will probably evaluate several factors to determine how aggressive it is. These "markers" identify whether the cancer is low risk, intermediate risk, or high risk. Low-risk prostate cancer is slow growing and not likely to spread quickly. High-risk prostate cancer is aggressive, meaning it is likely to spread quickly outside the prostate. Understanding the risk level of your cancer will help your doctor decide on the treatment that's right for you. Your doctor will look at key markers for aggressive cancer, as well as the stage of your specific cancer.