Malignant bone disease (osteosarcoma)
To understand the mechanisms of occurrence of a particular disease of bone tissue and bones in general (tumors, osteosarcomas), one should carefully study what bone and bone tissue are in themselves.
Bone is a specialized connective tissue that, like all connective tissues, contains cells and the extracellular matrix. The extracellular matrix is composed of organic and inorganic material.
With extensive damage to the bones by a tumor, most often with metastases of breast cancer, myeloma, and lymphoma, osteolytic hypercalcemia occurs, in which the waste products of tumor cells, for example, cytokines, stimulate local bone resorption by osteoclasts. Multiple myeloma may be the most common cause of pathological fracture requiring urgent surgery in some practice settings.
In solid tumors (osteosarcomas), bone resorption is stimulated by the tumor secreting peptides like a parathyroid hormone. Humoral paraneoplastic hypercalcemia occurs: tumor metabolites have a general effect, reducing calcium excretion.
PTH-like peptides have sections of the amino acid sequence similar to PTH, they act through the receptors for this hormone and are not detected by immunoassay. Growth factors, prostaglandins, and especially cytokines that activate osteoclasts, which are often elevated in leukemia, affect stimulating bone resorption.