RATIONALE: Hyperthermia therapy kills tumor cells by heating them to several degrees above normal body temperature. Drugs used in chemotherapy, such as mitomycin C and epirubicin hydrochloride, work in different ways to stop the growth of tumor cells, either by killing the cells or by stopping them from dividing. Biological therapies, such as bacillus calmette-guerin (BCG) and interferon alfa, may stimulate the immune system in different ways and stop tumor cells from growing. It is not yet known whether giving hyperthermia together with mitomycin C is more effective than giving BCG or standard therapy as second-line therapy in treating patients with recurrent bladder cancer.