A retrospective study of 90Strontium plesiotherapy for feline squamous cell carcinoma of the nasal planum

Abstract

The responses of 15 cats with histologically ( n=14) or cytologically ( n=1) confirmed nasal squamous cell carcinoma treated with 90Strontium plesiotherapy were reviewed retrospectively. Cats were treated such that a total dose of 50 Gy was delivered at a depth of 2 mm, administered in five fractions over a 10-day period. Of the cats, 11 were stage T2, three were Tis and one had only a cytological diagnosis precluding staging. Eleven of the cats achieved complete response (no visible lesion after 6–8 weeks) following the first cycle of therapy, and two cats with partial response achieved complete response with a second cycle of therapy. The remaining two cats achieved partial response following therapy, but further intervention was declined. Euthanasia was performed in these two cats because of progressive disease after 81 and 142 days. Of the 85% of cats that achieved a complete response, there was no recurrence of disease during a follow-up period of 134–2043 days (median 652 days). In addition to prolonged disease-free survivals, 90Strontium therapy produced excellent cosmetic results from the owners' perspective. These results demonstrate that superficial squamous cell carcinoma of the feline nasal planum responds excellently to 90Strontium plesiotherapy, and this form of therapy may offer advantages over other alternatives currently available.