The grade is a way to describe what cancer cells look like under the microscope and to the degree they appear abnormal. The degree of changes seen in the cells tells the pathologist how abnormal cancer cells are. Grade is defined as I, II, or III.
Grade I cancers are otherwise known as “well-differentiated” and appear very similar to normal cells. Their presence outside of the normal boundaries would define them as cancer. As cancers look increasingly abnormal, the grade gets higher. Thus, grade II cancers are moderately differentiated and grade III cancers are poorly differentiated.