TWO‐YEAR NON‐RECURRENCE RATES FOR EQUINE OCULAR AND PERIORBITAL SQUAMOUS CELL CARCINOMA FOLLOWING RADIOTHERAPY

Abstract

Seventeen horses with a total of 18 ocular or periorbital squamous cell carcinomas were irradiated with Strontium‐90 surface therapy, or Radon‐222, Iodine‐125, or Iridium‐192 interstitial implants. Tumors were surgically cytoreduced prior to irradiation in all but two horses. Follow‐up data was obtained for 2 years in each horse. Two‐year‐non‐recurrence rates (no grossly visible evidence of tumor) were 87.5% for 90 Sr beta therapy, and 60% (70% when corrected for non‐tumor‐related deaths) for interstitial implant therapy. Data regarding frequency of occurrence, location of lesions, age of onset, and non‐recurrence rates were similar to previous literature reports utilizing variable or shorter follow‐up periods. The effects of cytoreductive surgery of the tumors was not studied.