Once diagnosed, staging of cancer is necessary to make the treatment plan.
Cancer staging is done in two ways: TNM (Tumour, Node, Metastasis) staging and Number staging from I to IV. It was developed by the International Union against Cancer and the American Joint Committee on Cancer (AJCC).
- ‘T’ refers to the size of the primary tumor
- ‘N’ refers to whether the lymph nodes in the neck area have become cancerous
- ‘M’ refers to whether cancer has spread to distant organs in the body (metastasized), such as your lungs, bones, or liver
Stages progress from stage I to stage IV depending upon the aggressiveness of the cancer cells and the extent of spread.
Stage 1: In stage 1A, cancer is smaller than 8 centimeters across and has not spread to nearby lymph nodes or to distant sites. In stage 1B, cancer grows larger than 8 centimeters across and may occur at more than one place on the same bone. Stage 1 bone cancers are low grade (G0) or cannot be determined (GX).
Stage 2: In stage 2A, cancer is smaller than 8 centimeters across and has not spread to nearby lymph nodes or to distant sites. In stage 2B, cancer grows larger than 8 centimeters across and may occur at more than one place on the same bone. Stage 2 bone cancers are high grade (G2 or G3).
Stage 3: Stage 3 bone cancer is in more than one place on the same bone and has not spread to nearby lymph nodes or to distant sites. Stage 3 bone cancers are high grade (G2 or G3).
Stage 4: Stage 4 bone cancer can be of any size and may occur in more than one place on the same bone. Stage 4A cancer has not spread to lymph nodes but it has spread only to lungs (M1a). Stage 4B cancer may or may not have spread to lymph nodes, lungs or other bones. Stage 4 bone cancers can be of any grade.