Gleason grading is the most important method of grading prostate cancer in the world and was recommended by the World Health Organization in 1993. Many studies have shown that Gleason grading is an important factor in patient prognosis. The Gleason grade of prostate cancer is based on the growth pattern of the tumor (reflecting the degree of differentiation of the tumor gland) and the infiltration of the tumor in the mesenchyme, without focusing on its cellular pattern. the degree of differentiation (growth pattern) in the Gleason grade is divided into 5 grades from well differentiated (grade 1) to undifferentiated (grade 5). The degree of differentiation usually varies between parts in the same prostate cancer. Therefore, the Gleason grading of prostate cancer includes both major and minor growth patterns. The minor growth pattern means that such structures do not dominate the tumor but account for more than 5% of the total score by adding the grades of major and minor growth patterns. For example, Gleason grade 4 + 3 = 7. If the tumor has only one component, it will be 3 + 3 = 6. Gleason grade 2 and 3 are rare, because Gleason grade 1 is rare. Gleason score 6 and 7 are the most common. The Gleason grade 2-5 is considered to be a well differentiated cancer, 6-8 is considered to be a moderately differentiated cancer, and 9-10 is considered to be a poorly differentiated cancer. The epithelial cells of the normal prostate gland are arranged around the ductal lumen. In Gleason grade 1 to 3, the polarity of the epithelial cells remains and almost all glands have a lumen. in Gleason grade 4, the epithelial cells are partially depolarized, and in Gleason grade 5, the epithelial cells are almost completely depolarized and only occasionally have a lumen.