Grading

Grading describes how the cancer cells look compared to normal, healthy cells
Low-grade cancers have cancer cells that are well differentiated. The cells are abnormal but look a lot like normal cells and are arranged a lot like normal cells. Lower-grade cancers tend to grow slowly and are less likely to spread.
High-grade cancers have cancer cells that are poorly differentiated or undifferentiated. The cells don’t look like normal cells and are arranged very differently. Higher grade cancers tend to grow more quickly and are more likely to spread than low-grade cancers.

Grade I
Well differentiated, responds poorly to radiotherapy and are less aggressive

Grade II:
Moderately differentiated

Grade III:
Poorly differentiated, responds better to radiotherapy and are fast growing tumors with early metastasis.