The beneficial effects of diphosphonate and piroxicam on the osteolytic and metastatic spread of rat prostate carcinoma cells.

Transplantable rat prostate adenocarcinoma III cells produce local tumors and osteolytic and osteoplastic lesions and they metastasize through defined lymphatic channels to the lungs in which they produce expanding focal tumors. The bone lesions were prevented by treatments with dichloromethane diphosphonate (Cl2MDP). Treatment of rats with piroxicam, a nonsteroidal antiinflammatory drug, suppressed to some extent tumor growth, bone destruction, and metastasis. However, simultaneous treatments of rats with both drugs (Cl2MDP and piroxicam) prevented bone damage and suppressed tumor growth and metastatic spread very significantly without evidence of toxicity.