Introduction

External-beam-radiotherapy (RT) is commonly used to treat feline intranasal carcinomas (FINC); however, little is known regarding the comparative efficacy of various irradiation strategies. This multi-institutional retrospective study was performed to report outcomes and identify prognostic factors associated with survival for cats with FINC.

Methods

Medical records for patients with FINC that underwent RT at one of 7 veterinary RT facilities were retrospectively reviewed. Irradiation protocols were categorized as: definitive-intent full-course RT (FRT), definitive-intent stereotactic RT (SRT), and palliative-intent RT (PRT). Median overall survival time (mOST) and disease progression-free survival (mPFS; documented via CT/MRI) were calculated. The impacts that tumor stage, RT protocol/intent, and use of adjunctive therapies had on outcome were evaluated.

Results

Total 43 cats were included (18 SRT, 8 FRT, and 17 PRT). The mOST and mPFS were 453 days (95%CI; 226–679 days) and 357 days (144–570 days), respectively. In multivariable modeling, definitive-intent treatment (FRT or SRT) was associated with significantly longer mPFS (504 days vs. 159 days for PRT; p=0.048) and mOST (721 days vs. 282 days for PRT; p=0.047). Disease laterality also associated with mPFS; unilateral tumors that were treated with a definitive-intent RT had significantly longer mPFS (542 days) than their bilateral counterpart (357 days) and uni- or bi-lateral tumors that were treated palliatively (198 and 82 days, respectively).

Conclusion

Definitive-intent RT is associated with prolonged OST and PFS as compared to PRT in cats with FINC; local tumor control is longest in cats with unilateral tumors treated with definitive-intent RT.