**9.4 Remodeling of bone metastases**

Radiotherapy is the most important treatment for bone metastases. Long-term local control of the disease is possible.

In **Figure 12** we present a patient treated over years with bone metastases throughout the skeleton and taking advantage of radiotherapy with standard doses of 2 Gy per fraction and an accumulated total dose of 676 Gy to achieve tumor control. A survival of almost four years was possible. The primary tumor in the breast was treated by surgery followed by adjuvant chest wall radiotherapy in 1979. The first bone metastasis was irradiated in 8/1993 and the last palliative radiotherapy was applied in 5/1997 [6].

**Figure 12.**

*Irradiated regions of the bone skeleton in a patient with a breast tumor who survived 4 years with radiation therapy.*

#### *9.4.1 Bone metastasis and remodeling processes in the extracellular matrix*

Cellular processes at the level of bone metastasis: after homing of tumor cells endosteal, the tumor cells release endothelin, which, through its appropriate

### *The Remodeling in Cancer Radiotherapy DOI: http://dx.doi.org/10.5772/intechopen.102732*

receptors, interact with osteoblasts to stimulate their proliferation. This leads to the formation of new bone and growth, but such bone is weak and prone to fracture. Activated osteoblasts release receptor activator, that signals the proliferation and maturation of osteoclasts. They stimulate macrophages to produce pro-inflammatory cytokines and prostaglandins, which induce pain by binding to their receptors on sensory neurons.
