Prostate cancer is often treated with surgery or drugs to lower levels of testosterone and similar hormones called androgens. These hormones stimulate cancer cells to grow, so lowering their levels usually slows or stops the growth of cancer. However, these hormones also maintain the density and strength of men's bones, so lowering their levels also leads to weaker bones and more fractures. Drugs used to treat osteoporosis prevent weak bones and fractures, and therefore, they might be useful in preventing weak bones and fractures in men with prostate cancer who receive hormone-lowering treatment.