Retrospective evaluation of intranasal carcinomas in cats treated with external-beam radiotherapy: 42 cases.

BACKGROUND

Little is known regarding the comparative efficacy of various irradiation strategies used to treat intranasal carcinomas (INC) in cats.

OBJECTIVES

Investigate outcomes and prognostic factors associated with survival for cats with INC.

ANIMALS

Forty-two cats with INC that underwent radiotherapy (RT).

METHODS

Single-arm retrospective study. Medical record review for cats with INC that underwent RT at 1 of 7 veterinary RT facilities. Irradiation protocols categorized as: definitive-intent fractionated RT (FRT), definitive-intent stereotactic RT (SRT), and palliative-intent RT (PRT). Median overall survival time (OST) and disease progression-free survival (PFS; documented by advanced transverse imaging, or recurrence of symptoms) were calculated. Associations between tumor stage, RT protocol/intent, and adjunctive treatment usage and outcome were calculated.

RESULTS

Cats underwent SRT (N = 18), FRT (N = 8), and PRT (N = 16). In multivariate modeling, cats received definitive-intent treatment (DRT; FRT/SRT) had significantly longer median PFS (504 days, [95% confidence interval (CI): 428-580 days] vs PRT 198 days [95% CI: 62-334 days]; p = 0.006) and median OST [721 days (95% CI: 527-915 days) vs 284 days (95% CI: 0-570 days); p = 0.001]). Cats that underwent second DRT course at time of recurrence lived significantly longer than cats that received 1 RT course (either DRT or PRT [median OST 824 days (95% CI: 237-1410 days) vs 434 days (95% CI: 277-591 days); p = .028]).

CONCLUSION

In cats with INC, DRT is associated with prolonged OST and PFS as compared to PRT. If tumor progression occurs, a second course of DRT should be considered.