Treatment and outcome of four cats with apocrine gland carcinoma of the anal sac and review of the literature.

Anal sac adenocarcinoma is uncommon in cats. We report the outcome of multi-modality therapy in two cats (surgery, definitive radiotherapy and systemic chemotherapy) and surgery alone in two cats. All received surgical excision of the primary tumour followed by radiotherapy and carboplatin chemotherapy in two cases. Both cats that underwent multimodal therapy developed distant metastatic disease and one developed recurrence of the primary tumour. One cat that underwent surgery alone with incomplete margins also developed rapid recurrence. Overall survival times were 89, 161 and 169 days. One cat that had complete surgical excision is still alive without recurrence 425 days postoperatively. Whilst the role of radiation in the local control of this disease is yet to be defined, clearly a more effective systemic therapy is required before such aggressive local treatment can be routinely recommended.