Effects of treatment with and without adjuvant radiation therapy on recurrence of ocular and adnexal squamous cell carcinoma in horses: 157 cases (1985-2002).
OBJECTIVE
To determine the effects of treatment with and without adjuvant radiation therapy on recurrence of ocular and adnexal squamous cell carcinoma (SCC) at specific anatomic locations in horses.


METHODS
Retrospective study.


METHODS
91 horses.


METHODS
Medical records of horses with histologically confirmed ocular and adnexal SCC evaluated from 1985 to 2002 were reviewed. Sex, breed, age, type of treatment, location, and recurrence of SCC were recorded. Two treatment groups determined by recurrence of SCCs treated with and without adjuvant radiation therapy were established.


RESULTS
The anatomic site with the highest recurrence rate was the limbus (junction of the cornea and sclera) or bulbar conjunctiva (477%), independent of treatment group. There was a significant difference in recurrence rates of ocular and adnexal SCCs between the 2 treatment groups, independent of anatomic location. Recurrence rates of SCCs treated with and without adjuvant radiation therapy were 11.9% and 44.1%, respectively. Recurrence rates for SCCs of the eyelid, limbus or bulbar conjunctiva, and cornea treated with adjuvant radiation therapy were significantly different from those for SCCs treated without adjuvant radiation therapy. The most frequently represented anatomic site for ocular and adnexal SCCs was the eyelid (28.7%). Coat color, breed, and the interaction of age and breed had a significant effect on tumor recurrence regardless of treatment type and anatomic location.


CONCLUSIONS
Results indicated that ocular and adnexal SCCs treated with adjuvant radiation therapy had a significantly lower recurrence rate, compared with SCCs treated without adjuvant radiation therapy, independent of anatomic location.
Mosunic
Cory B
CB
Department of Small Animal Medicine and Surgery, College of Veterinary Medicine, University of Georgia, Athens, GA 30602-7371, USA.
Moore
Phillip A
PA
Carmicheal
K Paige
KP
Chandler
Matthew J
MJ
Vidyashankar
Anand
A
Zhao
Ying
Y
Roberts
Royce E
RE
Dietrich
Ursula M
UM
D000818:Animals; D002294:Carcinoma, Squamous Cell / Q000532:radiotherapy / Q000601:surgery / Q000662:veterinary*; D005134:Eye Neoplasms / Q000532:radiotherapy / Q000601:surgery / Q000662:veterinary*; D005260:Female; D006734:Horse Diseases / Q000532:radiotherapy / Q000601:surgery*; D006736:Horses; D008297:Male; D009364:Neoplasm Recurrence, Local / Q000517:prevention & control / Q000662:veterinary*; D011379:Prognosis; D018714:Radiotherapy, Adjuvant / Q000662:veterinary; D012189:Retrospective Studies; D016019:Survival Analysis