Histological studies of bone metastases show that tumour cells remain in the bone marrow cavity and secrete factors that regulate bone cells including parathyroid hormone related protein (PTHrP), tumour necrosis factor (TNF), interleukin-6 (IL-6) and transforming growth factor (TGF)β (Yin et al, 2005). Here, IL6 is linked to neoplasm.