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

Abstract

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.

Keywords: head and neck cancer; nasal cancer; nasal tumor; radiation therapy.

FIGURE 1

Kaplan‐Meier survival curves showing overall survival times (OST) in all cats (N = 42) with intranasal carcinoma treated with radiation therapy, grouped by treatment intent. A, Definitive; solid line, N = 26, median OST: 721 days, 95% confidence interval (CI): 527 to 915 days; B, Palliative; dashed line, N = 16, median OST: 284 days, 95% CI: 0 to 570 days. P value (<.05) of Cox univariate proportional hazard model comparing OST between treatment intent groups; (A) vs (B): <.001. Black symbols indicate censored cases

FIGURE 2

Kaplan‐Meier survival curves showing progression‐free survival (PFS) in all cats (N = 42) with intranasal carcinoma treated with radiation therapy, grouped by treatment intent. A, Definitive; solid line, N = 26, median PFS: 504 days, 95% confidence interval (CI): 428 to 580 days; B, Palliative; dashed line, N = 16, median PFS: 198 days, 95% CI: 62 to 334 days. P value (<.05) of Cox univariate proportional hazard model comparing PFS between treatment intent groups; (A) vs (B): .006. Black symbols indicate censored cases

FIGURE 3

Kaplan‐Meier survival curves showing progression‐free survival (PFS) in all cats (N = 41; information about disease laterality was not available in 1 cat) with intranasal carcinoma treated with radiation therapy, grouped by treatment intent (definitive vs palliative) and disease laterality (unilateral vs bilateral). A, Definitive, unilateral; solid line, N = 13, median PFS: 591 days, 95% confidence interval (CI): 439 to 743 days; B, Definitive, bilateral; long dashed line, N = 13, median PFS: 357 days, 95% CI: 56 to 658 days; C, Palliative, unilateral; short dashed line, N = 5, median PFS: 198 days, 95% CI: 114 to 282 days; D, Palliative, bilateral; dotted line, N = 10, median PFS: 98 days, 95% CI: 0 to 271 days. P value (<.05) of Cox univariate proportional hazard model comparing PFS between treatment intent groups: (A) vs (D) = .02. Black symbols indicate censored cases

FIGURE 4

Kaplan‐Meier survival curves showing progression‐free survival (PFS) in cats with intranasal carcinoma that underwent only 1 course of radiation therapy (N = 34), grouped by treatment intent (definitive vs palliative) and disease laterality (unilateral vs bilateral). A, Definitive, unilateral; solid line, N = 10, median PFS: 689 days, 95% confidence interval (CI): 541 to 837 days; B, Definitive, bilateral; long dashed line, N = 11, median PFS: 459 days, 95% CI: 0 to 1015 days; C, Palliative, unilateral; short dashed line, N = 3, median PFS: not reached, mean PFS: 316 days; D, Palliative, bilateral; dotted line, N = 10, median PFS: 98 days, 95% CI: 0 to 271 days. P value (<.05) of Cox univariate proportional hazard model comparing PFS between treatment intent groups: (A) vs (D) = .03. Black symbols indicate censored cases