Treatment of genitourinary carcinoma in dogs using nonsteroidal anti-inflammatory drugs, mitoxantrone, and radiation therapy: A retrospective study.

backgroundLocoregional tumor control and prolonged survival for dogs with genitourinary carcinoma (CGUC) reportedly are achievable using treatment with radiotherapy (RT) with or without adjunctive chemotherapy and nonsteroidal anti-inflammatory drugs (NSAIDs).

objectivesTo characterize event-free and overall survival after treatment of CGUC using NSAIDs, mitoxantrone (MTX), and a standardized RT protocol (57 Gy in 20 fractions). ANIMALS: Fifty-one client-owned dogs treated between 2008 and 2017.

methodsDogs were retrospectively categorized into treatment groups: (a) first-line concurrent chemoradiotherapy (≥1 dose of MTX started within 1 month of RT); (b) first-line chemotherapy (MTX administered for >1 month before RT without tumor progression); (c) RT as a salvage procedure (MTX, surgery or both with subsequent locoregional tumor progression before RT). Treatment-induced toxicoses, event-free survival (EFS), and overall survival times (OSTs) were recorded. The influence of demographics, staging, and treatment-related factors on survival was assessed using Cox proportional hazards modeling.

resultsMedian EFS and OST for all dogs were 260 and 510 days with no significant differences among groups 1 (n = 39), 2 (n = 4), and 3 (n = 8). Both EFS and OST were shorter in dogs with moderate to severe clinical signs (P < .001 and P < .001, respectively); OST was shorter in dogs with prostatic involvement (P = .02). Permanent urinary incontinence developed in 16 dogs (31%) at a median of 70 days postirradiation; other toxicoses were mild and self-limiting. CONCLUSIONS AND CLINICAL IMPORTANCE: Mild clinical signs and lack of prostate involvement were associated with favorable prognosis for survival. Client education regarding the risk of urinary incontinence is warranted.