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Safety and efficacy of stereotactic body radiation therapy ( SBRT ) for the treatment of canine thyroid carcinoma
Author(s) -
Lee BerIn,
LaRue Susan M.,
Seguin Bernard,
Griffin Lynn,
Prebble Amber,
Martin Tiffany,
Leary Del,
Boss MaryKeara
Publication year - 2020
Publication title -
veterinary and comparative oncology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.864
H-Index - 34
eISSN - 1476-5829
pISSN - 1476-5810
DOI - 10.1111/vco.12625
Subject(s) - medicine , thyroid carcinoma , toxicity , thyroid , metastasis , radiation therapy , carcinoma , retrospective cohort study , thyroid cancer , nuclear medicine , surgery , gastroenterology , cancer
Abstract Thyroid carcinoma develops spontaneously in dogs, with only 25% to 50% of cases amenable to surgery at diagnosis. Local control for unresectable tumours can be provided with external beam radiotherapy. The aim of this retrospective study is to describe the safety and efficacy of stereotactic body radiation therapy (SBRT) for treatment of canine thyroid carcinoma. Twenty‐three dogs met inclusion criteria; median tumour volume before SBRT was 129.9 cm 3 (range, 2.7‐452.8 cm 3 ). Sixteen patients (70%) had unresectable tumours. Pulmonary metastasis was present or suspected in 10 patients (44%) before SBRT. Patients were prescribed 15 to 40 Gy to targeted tumour volume in one to five fractions. Twenty patients evaluated had overall response rate of 70% (complete response, n = 4; partial response, n = 10). Thirteen out of sixteen (81%) symptomatic patients had clinical improvement within a median time of 16 days (range, 2‐79 days). Median progression free survival (MPFS) was 315 days. Median survival time (MST) was 362 days. Nine patients (39%) had grade 1 acute radiation toxicity. Three patients had grade 1 late radiation toxicity (two leukotrichia and one [4%] with intermittent cough). Responders had significantly longer MPFS (362 vs 90 days; HR 4.3; 95% CI 1.4‐13.5; P = .013) and MST (455 vs 90 days; HR 2.9; 95% CI 1‐8.4; P = .053). Presenting with metastasis was not a significant negative prognostic factor (MST 347 vs 348 days without metastasis; P = .352). SBRT is a safe and effective treatment modality for non‐resectable canine thyroid carcinoma.