Bone cancer can begin in any bone of the body, but it mostly affects the pelvis or long bones such as of the arms and legs. The tumor on pelvis first crosses the sacroiliac joint, which connects the bottom of the spine with the pelvis and then grows to the sacral neuroforamen. The tumor in the pelvis or hip region spreads to the femur which is a lower thigh bone. In later stages, the tumor grows around blood vessels or affects blood flow.
In stage 3 bone cancer, the cancer has spread to more places or adjacent parts in the same bone. Depending upon the location of the tumor, the size can be of about 8 cm. The tumors are supposed to be high-grade (G2 or G3) or poorly differentiated during this stage. The cancer has not spread to nearby lymph nodes and has not metastasized to distant sites in the body. [Image used under Cancer Research UK / Wikimedia Commons license]
During stage 1B bone cancer, the tumor is low grade or cannot be graded (G1 or GX) which means that the cancer looks similar to healthy tissue and contains different cell groupings. It is also called well differentiated tumor. The size of the tumor is larger than 8 cm. It is also possible that there is more than 1 separate tumor in the primary bone site. The tumor in stage 1B has not spread to any lymph nodes or to other parts of the body. [Image Source: Licensed from Cancer Research UK / Wikimedia Commons]
If a person is suffering from stage 2B bone cancer, the tumor is supposed to be high grade (G2 or G3) which means that the cancer cells are moderately or poorly differentiated. The size of the tumor is expected to be larger than 8 cm. At this stage, the tumor has not spread to any lymph nodes or to other parts of the body (N0, M0). [Image Source: Cancer Research UK / Wikimedia Commons]
In case of stage 2A bone cancer, the size of the tumor extends to up-to 8 centimeters (cm) across (about 3 inches). During this stage, the cancer is expected to be of high grade (G2 and G3). If the cancerous tissue looks very different from healthy tissue, it is called poorly differentiated and is supposed to be a high-grade tumor. The tumor in the bone does not spread to nearby lymph nodes (N0) or to distant sites (M0). [Image Source: Cancer Research UK / Wikimedia Commons]
The illustration shows a type of bone cancer - Osteosarcoma. The cancer produces immature bone. It is the most common type of cancer in bones and is usually found at the end of long bones, such as around the knee. It is estimated that osteosarcomas make up to more than 60% of primary bone cancers and also account for about 12 % of all childhood cancers. Osteosarcoma is supposed to be a very aggressive cancer and more than 80% of all cases are supposed to be highly malignant.