RATIONALE: Drugs used in chemotherapy, such as docetaxel, prednisone, and atrasentan work in different ways to stop the growth of tumor cells, either by killing the cells or by stopping them from dividing. Giving more than one drug (combination chemotherapy) may kill more tumor cells. It is not yet known whether docetaxel, prednisone, and atrasentan are more effective than docetaxel and prednisone in treating prostate cancer.