CXCL12 and cancer: The “vicious circle” hypothesis posits a reciprocal relationship between cancer cells and the bone microenvironment that catalyzes both tumor growth and bone destruction, a concept that is widely accepted as the primary mechanism driving BOM-RCC.[85] Research has shown that cancer cells possess a strong chemotactic response osteoblasts, which secrete chemokine family members such as CXCL12.