RATIONALE: Drugs used in chemotherapy, such as docetaxel, work in different ways to stop the growth of tumor cells, either by killing the cells or by stopping them from dividing. Androgens can cause the growth of prostate cancer cells. Antihormone therapy, such as leuprolide, may lessen the amount of androgens made by the body. Radiation therapy uses high energy x-rays to kill tumor cells. Giving docetaxel together with androgen ablation therapy and external-beam radiation therapy may kill more tumor cells.