In cancer, the word grade is used to describe how aggressive an illness it is. When a pathologist examines a biopsy sample under their microscope, they observe many different characteristics of the cancer cells. Depending upon what they see, they can predict how aggressive the tumor is likely to be in the future. Grading also takes into account how far along a cancer is, whether it has spread or not, and other conditions that are present. Each type of cancer has its own grading system, but generally, the more aggressive a tumor is, the higher the number assigned to it. A grade 1 tumor is less aggressive than a grade 2 tumor, for example. Some cancers use the words “high” and “low” instead of numbers to describe the grade, with high being most aggressive, and low least aggressive. If you hear your oncologist use words like “hot” or “angry” to describe a tumor, that also implies a higher grade, and a more aggressive tumor.