PTHLH and neoplasm: The initiator of the cycle is proposed to be the release of parathyroid hormone‐related protein (PTHrP) from tumor cells in response to the increased extracellular calcium[17] and transforming growth factor‐β (TGF‐β) found in the bone.[18] Tumor‐secreted cytokines such as interleukin‐6 (IL‐6)[19] along with PTHrP[20] instruct osteoblasts to release receptor activator of nuclear factor kβ ligand (RANKL) which consequently stimulates osteoclast activity.