# Reducing Recurrence in Equine Corneolimbal SCC: Outcomes of Adjunctive Cisplatin Biodegradable Bead Therapy

## TL;DR

Using cisplatin implants with surgery may reduce cancer recurrence in horses' eyes and is generally safe.

## Contribution

This study shows cisplatin biodegradable beads used with surgery may significantly reduce SCC recurrence in horses.

## Key findings

- Only 24% of horses treated with cisplatin beads had cancer recurrence, compared to a typical 50% recurrence rate.
- Most adverse effects were mild and temporary, with only two cases requiring closer monitoring.
- Vision was preserved in all but one horse that experienced a relapse.

## Abstract

Squamous cell carcinoma is a common ocular neoplasm in horses. Though the cancerous mass can sometimes be removed by surgery, it often grows back. In fact, the mass returns in about half of the treated horses. This study reviewed medical records from 17 horses with this neoplasm to see if combining surgery with a specific chemotherapy implant (on the eye itself) could help prevent mass recurrence. All horses were monitored for 1–5 years after treatment. Only 4 of the 17 horses (~24%) had the neoplasm return during the follow-up period. In terms of adverse effects, most were mild and temporary, like irritation or inflammation of the eye. Only two horses had adverse effects that needed closer follow-up. Overall, these findings suggest that using this specific chemotherapy implant as an adjunct treatment with surgery is generally safe and may decrease the chances of this cancer returning in horses.

(1) Context: Squamous cell carcinoma (SCC) is the most prevalent ocular neoplasm in horses, with a reported 45% recurrence rate when managed by surgery alone. (2) Objective: To evaluate the effect of adjunctive cisplatin biodegradable beads (CBBs) on recurrence rates of equine corneolimbal squamous cell carcinoma (SCC) and to document associated adverse effects. (3) Methods: Seventeen cases of histopathologically confirmed corneolimbal SCC in horses were retrospectively identified. Masses were surgically excised by keratectomy and/or conjunctivectomy under general anesthesia, followed by implantation of CBBs beneath conjunctival flaps at approximately 1 cm intervals around the excised area. Horses were monitored through owner follow-ups for up to five years postoperatively. (4) Results: Three horses (17.64%) experienced local mass recurrence within one year of treatment, and one horse (8.33%) relapsed approximately two years post-treatment. Minor local adverse effects—including chemosis (36%), hyperemia (64%), localized yellow discoloration (55%), and granular tissue formation (36%)—resolved within one to two months after surgery. Two horses developed bead-associated uveitis requiring closer ophthalmic monitoring. Vision was preserved in all but one relapsing case. (5) Conclusions: These findings suggest that adjunctive use of cisplatin biodegradable beads during surgical excision of equine corneolimbal SCC may significantly reduce recurrence rates and is generally well tolerated.