sentences:  According to the Bone Cancer Research Trust (BCRT), the most common symptoms are localized pain, swelling, and sporadic bone pain with variable intensity.The swelling is most likely to be visible if the sarcoma is located on a bone near the surface of the body, but when it occurs in other places deeper in the body, like on the pelvis, it may not be visible.Genetic exchange between chromosomes can cause cells to become cancerous.