Oral pamidronate in the prevention and treatment of skeletal metastases in patients with breast cancer.

Bone metastases are common in patients with breast cancer and cause considerable morbidity and deterioration of the quality of life. The main pathogenetic mechanism is stimulation of osteoclastic bone resorption by factors produced by the cancer cells. Pamidronate given intravenously suppresses bone resorption and is an effective treatment of malignancy-associated hypercalcemia. Recent data indicate that it can also reduce skeletal morbidity in normocalcemic patients with breast cancer and osteolytic metastases. In a series of studies we examined the long-term efficacy of oral pamidronate in the prevention and treatment of skeletal metastases in patients with breast cancer. In patients with bone metastases oral pamidronate given for a median period of about 20 months reduced significantly skeletal morbidity and had a favourable effect on selective aspects of the quality of life of the patients. Treatment did not alter the radiological course of the disease or the overall survival of the patients. In contrast, oral pamidronate given to patients with advanced breast cancer but no demonstrable bone metastases did not prevent or delay the appearance of the first clinical or radiological manifestation of bone metastases. This treatment is therefore very effective in patients with established metastatic bone disease. More studies are needed to define the place of pamidronate (and of other bisphosphonates) in the prevention of bone metastases in patients at risk.