The purpose of this study is to test the safety of different amounts (doses) of external radiation therapy (high-energy x-rays that shrink or destroy cancer) combined with 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