Retrospective study about the effect of Bremachlorin-based photodynamic therapy in nine dogs with transitional cell carcinoma of the urinary bladder and/or urethra

Abstract

Background: In this retrospective case study the effect of Bremachlorin photodynamic therapy was studied on transitional cell carcinomas (TCC) of the bladder and/or urethra in dogs. Methods: Nine dogs had confirmed TCC by cytology or histology and were treated by an intravenous injection of 60 mg/m² Bremachlorin. After 16-24 hours a laser fiber delivery system was passed transurethral in retrograde fashion and positioned at target area. Duration of light irradiation was calculated by formula T = J/cm² ÷ W/cm² (light intensity (W), diameter of the urethra (mm), total light doses (J) and irradiance (mW/cm²)). Number of treatments varied between one and five treatments depending on clinical signs during micturition. Therapeutic effect was assessed by ultrasonography of the urinary bladder and by interviewing the owner. Results: Initial clinical presentations were hematuria, dysuria and/or pollakisuria. Interval between start of clinical signs and start of treatment was 34-689 days. Median survival time was 179 days. Assessment of exact tumor volume by ultrasonography was inconsistent. Four of nine dogs regained an almost normal micturition pattern after treatment with subjectively larger volume of the urinary stream in three dogs. Three of the nine dogs showed intermittent improvement. Two dogs showed no improvement at all. One dog was lost to follow up after 392 days. All other dogs died due to disease. Toxic side effects were not seen after administering Bremachlorin. Conclusion: Bremachlorin is a promising photosensitizer for photodynamic therapy as palliative treatment in dogs with urological TCC, but further studies are necessary.