Stereotactic Radiotherapy Boost as Part of Tri-Modality Treatment for Bladder Preservation in Patients with Muscle-Invasive Bladder Cancer

Abstract

<h3>Purpose/Objective(s)</h3> To review our experience with bladder preserving tri-modality treatment (TMT) using stereotactic body radiotherapy (SBRT) boost for treatment of patients with muscle invasive bladder cancer (MIBC). <h3>Materials/Methods</h3> A total of 68 consecutive patients with cT2-4a bladder cancer underwent transurethral resection of bladder tumor (TURBT). TURBT was visibly complete in 26 cases. Patients received SBRT to the tumor or tumor bed in the bladder followed by conventionally fractionated RT (CFRT) to pelvis and total bladder with concomitant weekly radio-sensitizing chemotherapy. During SBRT, intravesical installation of isovolumetric saline through urinary catheter ensured adequate bladder filling. Response rate was assessed by cystoscopic evaluation and pelvic MRI or CT. Toxicities were reported per the RTOG acute and late Radiation Morbidity Scoring Schema. <h3>Results</h3> The median age of all patients was 76 years (35-92 years). A complete response (CR) was confirmed in 98.5% of the patients. After a median follow-up time of 18 months, 3 patients had a muscle-invasive recurrence. The overall survival (OS) and cancer-specific survival (CSS) rates at 2 years were 84.5% and 90.6%, respectively. Of the surviving patients, 86.3% have a disease-free and functioning bladder. All patients completed SBRT boost and 63% patients received concurrent Gemcitabine chemotherapy. Acute grade 3 gastrointestinal (GI) or genitourinary (GU) toxicities occurred in only 1.5% of the patients. Late grade 3 GU toxicity occurred in 4.4% of the patients. No patients experienced grade 4 GI or GU toxicities. <h3>Conclusion</h3> SBRT boost followed by chemoradiation to the pelvis was found to be a well-tolerated and effective treatment for MIBC patients who are either not candidates for cystectomy or who desire bladder preservation. Additional study is required to further evaluate this novel tri-modality treatment paradigm.