Image-Guided Radiation Therapy for Bladder-Cancer Patients Undergoing Radiotherapy and Concurrent Gemcitabine Chemotherapy

Inclusion Criteria: * MSKCC-reviewed pathologically proven diagnosis of primary bladder urothelial carcinoma without evidence of regional (nodal) or distant spread (cT1-T4a, Nx or N0). * Karnofsky Performance Scale (KPS) ≥ 70% * Age ≥18 years old * Adequately functioning bladder, defined as continent and without the need for an indwelling catheter * Absolute neutrophil count (ANC) ≥ 1500/mL; platelets ≥ 100,000/mm3 serum bilirubin \< 1.5 x the upper limit of normal (ULN); aspartate aminotransferase (AST) and/alanine aminotransferase (ALT) ≤ 1.5 × ULN * Adequate renal function: calculated creatinine clearance \> 30 mL/min/1.73 m2 using the following formula modified Cockcroft and Gault Formula for estimated Creatinine Clearance * Patients must be considered able to tolerate systemic chemotherapy and pelvic radiation therapy. * Patients must have the ability to understand and the willingness to sign a written informed consent document Exclusion Criteria: * Evidence of distant disease or histologically-proven nodal metastases. Patients with radiologic evidence of lymphadenopathy must have biopsy proof of N0 status. * Previous pelvic radiation therapy * Prior systemic chemotherapy non-cisplatin based neoadjuvant for urothelial carcinoma (prior intravesical chemotherapy or immunotherapy is permissible) * Prior cisplatin based neoadjuvant systemic chemotherapy for more than \>4 cycles * Active inflammatory bowel disease (i.e., Crohn's disease or ulcerative colitis) * Women who are pregnant or lactating