Grading describes the appearance of the cancer cells under the microscope. The grade gives an idea of how quickly the cancer may develop. There are three grades: grade 1 (low grade), grade 2 (moderate grade) and grade 3 (high grade). Low grade means that the cancer cells look very like the normal bone cells. They are usually slow growing and are less likely to spread. In high-grade tumours the cells look very abnormal. They are likely to grow more quickly and are more likely to spread.

The stage of a cancer is a term used to describe its size and whether it has spread beyond its original site. Knowing the extent of the cancer and the grade helps the doctors to decide on the most appropriate treatment. There are three stages of bone cancer, partly based on the grade of your cancer.

Stage 1 bone cancer is low-grade and has not spread to lymph nodes or any other body organs.

Stage 1A means low-grade bone cancer that is still completely inside the bone in which it started. The cancer may be pressing on the bone wall and causing a swelling, but has not grown through it. Stage 1B bone cancer is low-grade, but has grown through the bone wall.

Stage 2 bone cancer is high-grade and has not spread to lymph nodes or any other body organ.

Stage 2A means the cancer is still completely within the bone in which it started. Stage 2B has grown through the wall of the bone.

Stage 3 is bone cancer of any grade that has spread beyond the bone in which it started to other organs in the body, such as the lungs.

Recurrent bone cancer means that the bone cancer has come back after initial treatment.