Endocrine aspects of bone metastases.

Skeletal lesions are a frequent complication of breast and prostate cancer and a hallmark of multiple myeloma. Endocrine and paracrine factors modulate various aspects of bone metastases, including tumour proliferation, skeletal susceptibility to tumour homing, the microenvironment needed to support tumour persistence, and the initiation of a vicious cycle between tumour and bone-resident cells that further promotes tumour growth. Endocrine changes, such as oestrogen or vitamin D deficiency, contribute to a fertile bone microenvironment that might promote bone metastases. Bone health could be impaired further by existing cancer treatments, especially sex hormone deprivation. In this Review, we discuss the effect of hormones and associated local factors on cross-talk between bone metabolism and tumour biology. We review the biology of osteolytic and osteosclerotic lesions, with a focus on endocrine aspects, and outline potential therapeutic targets. We also summarise endocrine aspects of the pathogenesis and clinical presentation of bone metastases and provide an update on existing and future treatments.