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. 2023 Mar;37(2):635-647.
doi: 10.1111/jvim.16644. Epub 2023 Feb 27.

Thyroidectomy in dogs with thyroid tumors: Survival analysis in 144 cases (1994-2018)

Daniela Enache  1 , Livia Ferro  1 , Emanuela M Morello  2 , Federico Massari  3 , Giorgio Romanelli  4 , Stefano Nicoli  1 , Stefano Guazzetti  5 , Federico Porporato  1 , Eric Zini  1   6   7
Affiliations

Thyroidectomy in dogs with thyroid tumors: Survival analysis in 144 cases (1994-2018)

Daniela Enache et al. J Vet Intern Med. 2023 Mar.

Abstract

Background: Few studies have assessed predictors of outcome in dogs with thyroid tumors undergoing thyroidectomy.

Objective: To estimate the survival and identify prognostic factors in dogs with thyroid tumors treated by thyroidectomy.

Animals: A total of 144 client-owned dogs with thyroid neoplasia that underwent thyroidectomy.

Methods: Retrospective study. Data for analysis included hospital attended and year of surgery, signalment, thyroxine concentration, thyroid tumor features (lobe involvement, size, invasiveness, histopathological type), thrombosis, metastasis, additional surgery and therapy, administration of adjuvant chemotherapy. The association of predictors with survival (time from surgery to death) were assessed by calculating cause-specific hazard ratios (HRcs ) and 95% confidence intervals (CI). Causes of death were classified as thyroid-related or because of other cause.

Results: Overall median survival time was 802 days (CI95% = 723-1015 days); 89 dogs (77.4%) survived >500 days. Metastases were identified at admission in 12 (8.3%) dogs and were associated with higher thyroid cancer-related fatality (HR = 5.83, CI95% = 1.56-21.78; P = .009). Thrombosis occurred in 40 dogs and was associated with increased risk of death because of other cause (HR = 2.73, CI95% = 1.18-6.35; P = .019). Nonfollicular carcinoma (HR = 4.17, CI95% = 1.27-13.69; P = .018) and administration of chemotherapy (HR = 3.45, CI95% = 1.35-8.82; P = .01) were associated with higher risk of thyroid cancer-related death.

Conclusions and clinical importance: Dogs with thyroid tumors undergoing thyroidectomy have a long life expectancy. Despite the rare presence of nonfollicular carcinoma and metastases, thyroidectomy should still be considered in some of these dogs.

Keywords: canine; carcinoma; competing risks analysis; follicular; metastasis; surgery.

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Conflict of interest statement

Eric Zini serves as Associate Editor for the Journal of Veterinary Internal Medicine. He was not involved in review of this manuscript. No other authors have a conflict of interest.

Figures

FIGURE 1
FIGURE 1
Kaplan‐Meier estimate of overall survival (ie, regardless of the death cause) and cumulative incidence (mortality) functions for each of the 2 outcomes (death by thyroid cancer and death by other cause).
FIGURE 2
FIGURE 2
CIFs for each of the 2 outcomes for subjects with or without metastasis at the time of surgery.
FIGURE 3
FIGURE 3
CIFs for each of the 2 outcomes for subjects with follicular or nonfollicular thyroid cancer.
FIGURE 4
FIGURE 4
CIFs for each of the 2 outcomes for subjects with or without thrombosis at the time of surgery.
FIGURE 5
FIGURE 5
CIFs for each of the 2 outcomes for subjects with or without postoperative chemotherapy.
See this image and copyright information in PMC

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