Prognostic factors in cats with squamous cell carcinoma treated with electrochemotherapy

Electrochemotherapy (ECT) has emerged as a valuable therapeutic option for feline cutaneous squamous cell carcinoma (SCC). However, the influence of clinicopathological variables on treatment outcomes remains insufficiently defined. This study included 35 cats with histopathologically confirmed SCC that underwent electrochemotherapy following intravenous administration of bleomycin (15,000 IU/m²). Animals were followed up, and clinicopathological data were collected, including muscle condition score (MCS), body condition score (BCS), tumor size, staging, necrosis, mitotic count, perineural invasion, tumor budding, treatment response, and toxicity. Early-stage tumors (T1-T2) were identified in 31.4% of cats, whereas 68.6% presented advanced-stage tumors (T3-T4). The objective response rate was 100%, with 65.7% achieving complete response (CR) and 34.3% partial response (PR). Median overall survival was 300 days, and median progression-free survival was 285 days. The median tumor diameter was 2.3 cm, and tumors exceeding this value were associated with increased odds of higher toxicity grades (OR 23.1; p < 0.001) and partial response to ECT (OR 36.6; p = 0.003). Multivariable analysis identified an increased risk of disease progression in cats with reduced MCS and BCS (HR 4.69; p = 0.011) and in those achieving PR to ECT (HR 14.98; p < 0.001). Similarly, reduced MCS and BCS (HR 4.68; p = 0.017) and PR to ECT (HR 22.24; p < 0.001) were independent risk factors for death. These findings highlight the clinical relevance of tumor size, treatment response, and nutritional status in cats with SCC treated with ECT.