Combined keratectomy, strontium-90 irradiation and permanent bulbar conjunctival grafts for corneolimbal squamous cell carcinomas in horses (1990-2002): 38 horses.

This research studied the success rate of using postoperative strontium-90 irradiation along with superficial keratectomy and permanent bulbar conjunctival graft to treat horses with corneolimbal squamous cell carcinoma (SCC) eye cancer, with a focus on reducing recurrence rate. The treatment methodology proved effective in about 83% of the cases, with a recurrence rate of approximately 17%.

Research Methods

• The retrospective case study is based on 38 horses that were diagnosed and treated for SCC of the eye, a common cancer in horses that impacts the limbus and/or cornea. SCC can result in vision loss, or even loss of the eye, if not properly managed.
• The horses were treated between 1990 and 2002. Each horse underwent strontium-90 irradiation, an uncommon form of beta radiation, directly after corneal and conjunctival graft surgery. The radiation was administered to aid in killing any remaining cancer cells.
• Recurrence was determined postoperatively and postirradiation if the SCC regrew in the same site and eye that had been previously treated.

Key Findings

• The majority of the horses treated were either partially or completely white in color, chestnut/sorrel colored, or gray. The Appaloosa breed was identified as the most common breed for SCC development. This could indicate a potential correlation between certain colorings or breeds and a predisposition to SCC.
• Eight horses (21%) could not be assessed for tumor recurrence due to lack of two or more follow-up examinations. Another horse needed to have its eye removed 6 days post-operatively due to a worsening corneal ulceration.
• Out of the remaining horses, 24 (63% of total; 83% of the followed cases) went a mean of 1754 days (~4.8 years) without SCC recurrence, with a range of 14 to 5110 days (up to approximately 14 years).
• Five horses (13% of total; 17% of the followed cases) exhibited tumor recurrence at a mean of 449 days (~1.23 years) with a range of 29 to 900 days (up to ~2.5 years). The five horses with recurring cancer were treated with local excision, enucleation, or additional strontium-90 therapy.

Conclusion

• The combination of superficial keratectomy, strontium-90 beta-irradiation, and permanent bulbar conjunctival grafts was demonstrated to be effective in managing corneolimbal, corneal, or corneolimbal SCC in horses in around 83% of the cases.
• The recurrence rate stood at about 17% among the horses.
• The authors recommend multiple biannual re-examinations to keep an eye on potential tumor recurrence.