Paclitaxel and Radiation Therapy With or Without Trastuzumab in Treating Patients Who Have Undergone Surgery for Bladder Cancer

You may be eligible if

• Histologically or cytologically confirmed primary transitional cell carcinoma (TCC) of the bladder
• * Histologic evidence of muscularis propria invasion
• Meets 1 of the following stage criteria:
• * Stage T2-4a; NX, N0, or N1; and M0 disease
• * Clinical stage T1, grade 3/3 disease AND requires definitive local therapy
• Tumor involvement of the prostatic urethra allowed provided the following criteria are met:
• * Tumor was visibly completely resected
• * No evidence of stromal invasion of the prostate
• * No evidence of distant metastases by chest x-ray (or chest CT scan) within 8 weeks prior to registration
• * No evidence of distant metastases by abdominal/pelvic CT scan (or MRI scan) within 8 weeks prior to registration
• Has undergone transurethral bladder resection (as thorough as is judged safely possible) within the past 3-8 weeks, including bimanual examination with tumor mapping
• Sufficient tumor tissue available for HER2/neu analysis
• Not a candidate for radical cystectomy
• Performance status - Zubrod 0-2
• Absolute neutrophil count \>= 1,800/mm\^3
• Platelet count \>= 100,000/mm\^3
• Hemoglobin \>= 8.0 g/dL (transfusion or other intervention allowed)
• Bilirubin \< 2.0 mg/dL
• Serum glutamic oxaloacetic transaminase (SGOT) and serum glutamate pyruvate transaminase (SGPT) \< 2.5 times upper limit of normal
• No hepatic insufficiency resulting in clinical jaundice and/or coagulation defects
• Creatinine =\< 3.0 mg/dL
• Left ventricular ejection fraction (LVEF) \>= 40% by multigated acquisition scan (MUGA) scan or echocardiogram
• No unstable angina and/or congestive heart failure requiring hospitalization within the past 6 months
• No transmural myocardial infarction within the past 6 months
• Not pregnant or nursing
• No nursing for 6 months after completion of study treatment (for patients receiving trastuzumab \[Herceptin®\])
• Negative pregnancy test
• Fertile patients must use effective contraception during and for 6 months after completion of study treatment
• Able to tolerate systemic chemotherapy and pelvic radiotherapy
• No other invasive malignancy within the past 3 years except nonmelanoma skin cancer
• No history of allergic reaction to study drugs
• No history of inflammatory bowel disease
• No acute bacterial or fungal infection requiring IV antibiotics
• No AIDS
• No other severe active comorbidity
• No prior systemic chemotherapy with anthracyclines or taxanes
• No prior systemic chemotherapy for TCC
• No prior pelvic radiotherapy