PURPOSE: Concomitant treatment with radiation therapy and cisplatin (CDDP) remains the gold standard for bladder preservation in the treatment of muscle-invasive bladder cancer (MIBC). We present the long-term results of a phase 1 clinical trial to assess the association of twice-weekly gemcitabine with CDDP and radiation therapy in this setting. METHODS AND MATERIALS: Patients with pT2-pT4N0M0 MIBC without hydronephrosis or diffuse carcinoma in situ were enrolled in this study. After maximal transurethral resection of the bladder tumor, patients received concomitant radiation therapy (63 Gy in 1.8 fractions) and chemotherapy (CDDP 20 mg/m²/day over 4 days every 21 days and gemcitabine twice a week). The starting dose of gemcitabine was 15 mg/m² with dose escalation to 20, 25, and 30 mg/m². The primary endpoint was the maximum tolerated dose (MTD). Secondary endpoints included toxicity and tumor control. RESULTS: Fourteen patients were enrolled. Dose-limiting toxicity occurred in 2 patients treated with 30 mg/m² gemcitabine (grade 4 thrombocytopenia and severe impairment of World Health Organization performance status, respectively). Nine patients received the complete chemoradiation therapy protocol. The recommended dose of gemcitabine was 25 mg/m². The median follow-up time was 53 months, and the overall and disease-specific 5-year survival rates were 62% and 77%, respectively. Among the patients who received the complete treatment, bladder-intact survival was 76% at 5 years, and the median overall survival was 69.6 months. CONCLUSIONS: This regimen was well tolerated. The gemcitabine MTD was 25 mg/m². Bladder preservation and disease control were promising. A multicenter phase 2 randomized trial is ongoing.