Intralesional sustained-release chemotherapy with therapeutic implants for treatment of canine sun-induced squamous cell carcinoma.

Squamous cell carcinoma (SCC) is the most frequently reported malignant epithelial tumour in dogs. Canine sun-induced SCC represents a useful animal model to evaluate new therapeutic modalities for possible human applications. We evaluated the safety and efficacy of treating sun-induced SCC in dogs with intralesional sustained-released chemotherapeutic gel implants that contained collagen, epinephrine (epi), and either 5-fluorouracil (5-FU) or cisplatin (CDDP). Dogs with large, single SCC or fields of multiple SCC were treated with 5-FU/epi gel for a minimum of three weekly injections. Dogs without a complete response were then treated with CDDP/epi gel for a minimum of three weekly treatments. We treated from one to 11 primary, recurrent, or refractory SCC per dog (tumour size 0.2-92.4 cm2; mean cumulative tumour area of 40.7 cm2 per dog). All dogs had at least 50% reduction in cumulative tumour area after treatment with 5-FU/epi gel. More than half (seven of 13) had complete resolution of SCC after treatment with 5-FU/epi gel or CDDP/epi gel. Minimal local tissue reactions were noted; no systemic toxicity occurred. Sustained-release chemotherapy using intralesional 5-FU/epi gel and CDDP/epi gel therapeutic implants is effective in treating canine sun-induced SCC of the skin.