Bladder Preservation for Patients With Muscle Invasive Bladder Cancer (MIBC) With Variant Histology

This study is exploring bladder preservation (keeping the bladder instead of removing it) as a treatment option for people with muscle-invasive bladder cancer that has an unusual or mixed cell type (called variant histology). This approach combines radiation, chemotherapy, and other treatments to try to destroy the cancer without surgery. **You may be eligible if...** - You have been diagnosed with muscle-invasive bladder cancer with a variant (uncommon) cell type - Your cancer is confirmed to be localized (stages T2–T4, no distant spread), confirmed by biopsy and imaging scans - You are willing and able to consent and follow the study procedures **You may NOT be eligible if...** - There is widespread superficial cancer spread (diffuse CIS) in your bladder - You have blockage in both kidneys (bilateral hydronephrosis) - You have previously received pelvic radiation - You have previously received systemic therapy for bladder cancer - You currently have another active cancer (past cancer more than 5 years ago is generally acceptable) Talk to your doctor to see if this trial is right for you.