Background: Single-dose administration of intravesical gemcitabine is a common part of clinical practice following transurethral resection (TURBT) of non-muscle invasive bladder cancer (NMIBC). Although the side effect profile for gemcitabine is well characterized in systemic and local therapy, rare side effects continue to be identified with ongoing use. Here we identify several cases of treatment-related alopecia with adjuvant single dose intravesical administration for NMIBC after TURBT. Methods: Using our single-institutional IRB-approved Cysview registry database, we identified patients who underwent TURBT for NMIBC and received a single dose of intravesical gemcitabine post-TURBT between January 2020 and June 2023 at Keck Hospital of USC. Patients with a history of low grade NMIBC or those undergoing their first TURBT received 2g of gemcitabine dissolved in 100 cc of saline 1h after tumor resection. We reviewed patient-reported adverse events and included patients who reported alopecia following gemcitabine instillation. Patients were questioned on the degree and length of hair loss and information was collected from patient charts. Results: Overall, 9 patients (2 male, 7 female) reported hair loss following single dose intravesical gemcitabine after the TURBT. One patient had an autoimmune disease. The hair loss started within a few days of gemcitabine instillation and resolved spontaneously. The table shows the clinicopathologic characteristics of this cohort in detail. Three patients experienced severe hair loss. The resection extent during TURBT was classified as small (<2 cm), medium (2-5 cm), or large (>5 cm). Three patients had a large resection, 2 patients a medium one and 3 patients a small resection. None of the patients had previous intravesical gemcitabine; however, 2 patients had a history of intravesical BCG and 1 had intravesical mitomycin before. Conclusions: This study demonstrates that hair loss is a rare but possible adverse effect of intravesical gemcitabine after TURBT. Prior to surgery, patients should be counseled regarding this potential side-effect. Additional research and multicenter studies are required to describe the occurrence and cause of this adverse event.

LG= Low Grade, HG = High Grade.