Direct resorption of bone by human breast cancer cells in vitro [19]

OSTEOLYTIC bone metastases occur frequency in patients with advanced malignancy. Breast cancer, the most common malignant disease of women, metastasises to bone more frequently than to any other organ¹, and over 80% of patients with advanced breast cancer develop bone metastases ^2-4. The cellular and molecular mechanisms of bone destruction in patients with cancer are not clearly understood. It has been postulated that there may be two mechanisms, one which is mediated by osteoclasts and one which occurs independently of osteoclasts^5,6. We show here that cultured human breast cancer cells have the capacity to resorb directly in vitro, independently of osteoclast stimulation.