We have developed a novel bladder preservation therapy, balloon-occluded arterial infusion (BOAI) of cisplatin/gemcitabine, concomitantly with hemodialysis, along with concurrent irradiation [the so-called 'OMC (Osaka Medical College) regimen']. The OMC regimen delivers an extremely high concentration of anticancer agent to the site of a tumor without systemic adverse effects, since more than 95% of free Pt was efficiently eliminated by hemodialysis, which enables short hospital stay. In this study, we investigated the efficiency of OMC regimen in patients aged over 70 years with muscle-invasive bladder cancer without metastasis. A total of 134 such patients were assigned to receive either the OMC regimen (n=89) or cystectomy (n=45). OMC regimen patients who failed to achieve CR underwent cystectomy, or secondary BOAI with gemcitabine (1,600 mg). The OMC regimen, which delivers an extremely high concentration of anticancer agent to the tumor site without systemic adverse effects, yielded CR in >91% (81/89) of patients. More than 96% (78/81) of the CR patients survived without recurrence with intact bladder after a mean follow-up of 164 (range 16-818) weeks. The 5- and 10-year bladder intact survival rates were 87.2 and 69.8%, and overall survival rates were 88.4 and 70.7% (vs. 59.9 and 33.3% for cystectomy, p=0.0002), respectively, although the median age in the OMC regimen group was significantly greater than in the cystectomy group (median, range = 77, 70-98 vs. 74, 70-89; p=0.0003). No patients suffered grade II or more severe toxicities; the oldest patient, aged 91 years, successfully completed this therapy. In conclusion, the OMC regimen is a useful bladder preservation strategy for elderly patients with locally invasive bladder cancer, not only in those for whom cystectomy is indicated, but also in patients whose condition is not amenable to curative treatment and for whom palliation would otherwise seem the only option.