External beam radiotherapy for small cell carcinoma of the urinary bladder: The Memorial Sloan-Kettering experience.

Abstract

290 Background: To report our experience using definitive external beam radiotherapy for small cell carcinoma of the urinary bladder. Methods: We reviewed records of 17 patients (14 male, 3 female) with small cell carcinoma of the urinary bladder treated at our institution with external beam radiation therapy (median dose 64.8Gy) for small cell carcinoma of the bladder between January 1994 and June 2011. Median age was 69 years. Sixteen (94.1%) patients received neoadjuvant and/or concurrent platinum-based chemotherapy. All patients underwent pretreatment maximal transurethral resection (visibly complete (n=7); incomplete (n=10). Seven patients had radiographic or pathologic evidence of nodal spread. Patients were followed with cystoscopy and radiographic imaging post-RT. Median followup was 7 months (range, 2-161 mos). Acute (<90days) and late (≥90days) toxicity was recorded using CTCAE v 3.0. Kaplan Meier method was used for survival analysis. Results: The 2-year overall survival was 62%. Of 17 patients, 3 patients developed local recurrence (LR) with a median time to local recurrence of 19 months. Two of three patients had noninvasive LR managed with transurethral resection and had no evidence of disease at last followup. One patient with invasive LR had both LR and distant metastasis identified <3 months after RT. Four patients developed distant metastases at a median time to progression of 2.5mos in bone (n=2), lung (n=1), and retroperitoneal lymph nodes (n=1). All but one patient with distant metastases had node-positive disease at diagnosis. The 2y distant metastasis-free survival for node (-) and node (+)patients was 90% and 30% (p=0.03). Of 12 patients currently without evidence of disease, 5 have followup ≥30mos. The incidence of grade ≥2 acute and late GU/GI toxicity was 53% and 6% respectively. Conclusions: Bladder preservation therapy for small cell carcinoma is feasible with encouraging early results. Nodal disease portends a poor prognosis. Brain metastases are uncommon suggesting a limited role for prophylactic cranial irradiation. Radiation therapy with concurrent platinum-based chemotherapy was associated with a low risk of late GU/GI toxicity in our cohort.