Perioperative intratumoral administration of cisplatin for treatment of cutaneous tumors in Equidae

Abstract

Twenty-seven horses (and 1 mule) with 32 histologically confirmed cutaneous tumors were studied to evaluate the effects of intratumoral injection of cisplatin initiated at the time of surgery. As a result of surgery, 9 of the wounds were closed primarily (5 sarcoids, 4 carcinomas) and 23 were left open to granulate (16 sarcoids, 6 carcinomas, 1 hamartoma). Chemotherapy consisted of 4 treatment sessions of intratumoral injection of cisplatin in purified sesame oil at 2-week intervals. The first treatment session was administered intraoperatively. A controlled-release formulation of cisplatin in sesame oil was used to limit drug egress from the injection site. Dosage was 1 mg of cisplatin/cm3 of tissue. The mean relapse-free interval was 41 ± 3.7 months. The estimates of overall relapse-free survival rates were 92 ± 5% at 1 year and 77 ± 11% at 4 years. Cisplatin-related local toxicosis was minimal and wound healing was not compromised. Intratumoral injection of cisplatin appears safe and effective when administered in the perioperative period for selected tumors in equidae.