Grading anal cancer
To find out the grade of anal cancer, the pathologist looks at a tissue sample from the tumour under a microscope. The pathologist gives anal cancer a grade from 1 to 4. The lower the number, the lower the grade.
The grade is a description of the differentiation of the cancer cells. Differentiation is how the cancer cells look and behave compared to normal cells.
Low grade means that the cancer cells are well differentiated. They look and act much like normal cells. Lower grade cancer cells tend to be slow growing and are less likely to spread.
High grade means that the cancer cells are poorly differentiated or undifferentiated. They look and act less normal, or more abnormal. Higher grade cancer cells tend to grow more quickly and are more likely to spread.
Knowing the grade gives your healthcare team an idea of how quickly the cancer may be growing and how likely it is to spread. This helps them plan your treatment. The grade can also help the healthcare team predict how you might respond to treatment.
American Joint Committee on Cancer. AJCC Cancer Staging Handbook. 7th ed. Chicago: Springer; 2010.
American Society of Clinical Oncology. Anal Cancer. 2014: http://www.cancer.net/cancer-types/anal-cancer.