Clinical outcomes and prognostic factors of repeated conventional hypofractionated radiotherapy for recurrent intranasal tumors in dogs

Background: Despite an initial favorable response to hypofractionated radiotherapy (RT), intranasal neoplasia has a poor long-term prognosis. Re-irradiation (re-RT) has been shown to result in clinical remission in dogs with recurrent intranasal tumors. Hypofractionated re-RT is indicated in cases...

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Main Authors: Hirona Ueno, Yuta Nishiyama, Takuya Maruo, Yohei Fukuda, Takayuki Katayama, Shinichiro Yoda, Kotaro Nishi, Hideki Kayanuma
Format: Article
Language:English
Published: Tripoli University 2025-02-01
Series:Open Veterinary Journal
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Online Access:http://www.ejmanager.com/fulltextpdf.php?mno=226692
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author Hirona Ueno
Yuta Nishiyama
Takuya Maruo
Yohei Fukuda
Takayuki Katayama
Shinichiro Yoda
Kotaro Nishi
Hideki Kayanuma
author_facet Hirona Ueno
Yuta Nishiyama
Takuya Maruo
Yohei Fukuda
Takayuki Katayama
Shinichiro Yoda
Kotaro Nishi
Hideki Kayanuma
author_sort Hirona Ueno
collection DOAJ
description Background: Despite an initial favorable response to hypofractionated radiotherapy (RT), intranasal neoplasia has a poor long-term prognosis. Re-irradiation (re-RT) has been shown to result in clinical remission in dogs with recurrent intranasal tumors. Hypofractionated re-RT is indicated in cases of recurrence. Aim: This study aimed to investigate the response of patients with recurrent intranasal tumors who were initially treated with repeated hypofractionated RT. Methods: Medical records of dogs with intranasal tumors that relapsed after undergoing hypofractionated RT at Azabu University Veterinary Teaching Hospital and who underwent re-RT between 2008 and 2022 were retrospectively analyzed. Results: Among the 30 dogs included, 20 had adenocarcinomas. Eleven patients underwent second re-irradiation, and five patients underwent third re-irradiation. The median total isocenter dose and total number of fractions were 56 Gy (range, 37.5–102) and 8 fractions (range, 5–14), respectively. The first, second, and third progression-free intervals (PFI) were 315 (n = 30), 185 (n = 11), and 218 days (n = 4), respectively. Overall survival (OS) was 504 days (n = 30). Adverse events such as alopecia (n = 7), white hair (n = 8), cataracts (n = 9), pigmentation (n = 5), keratitis (n = 3), and corneal ulceration (n = 1) were limited to grades 1 and 2. The medians of the first PFI for one course and two or more courses of re-RT were 298 and 331 days, respectively, indicating no significant differences between the groups. The OS after two or more courses of re-RT (758 days) was significantly longer than after one course of re-RT alone (414 days) (P = 0.048). However, the cases were not randomized and most of the tumor types were adenocarcinomas. Conclusion: Since it is expected to prolong survival time with few life-threatening adverse events, the findings of the present study suggest that hypofractionated re-RT can be used in dogs with recurrent intranasal tumors initially treated with hypofractionated RT. Therefore, repeated hypofractionated re-RT may be a reasonable option for young dogs with a good initial response and recurrent intranasal tumors. [Open Vet J 2025; 15(2.000): 827-834]
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spelling doaj-art-e1a3d47ecfdf41cea27f9daa807101512025-08-20T02:16:03ZengTripoli UniversityOpen Veterinary Journal2226-44852218-60502025-02-0115282783410.5455/OVJ.2025.v15.i2.32226692Clinical outcomes and prognostic factors of repeated conventional hypofractionated radiotherapy for recurrent intranasal tumors in dogsHirona Ueno0Yuta Nishiyama1Takuya Maruo2Yohei Fukuda3Takayuki Katayama4Shinichiro Yoda5Kotaro Nishi6Hideki Kayanuma71-17-71 Fuhinobe, Chuo, Sagamihara, Kanagawa 252-5201 Japan -17-71 Fuhinobe, Chuo, Sagamihara, Kanagawa 252-5201 Japan 1-17-71 Fuhinobe, Chuo, Sagamihara, Kanagawa 252-5201 Japan 1-17-71 Fuhinobe, Chuo, Sagamihara, Kanagawa 252-5201 Japan 1-17-71 Fuhinobe, Chuo, Sagamihara, Kanagawa 252-5201 Japan 1-17-71 Fuhinobe, Chuo, Sagamihara, Kanagawa 252-5201 Japan 1-17-71 Fuhinobe, Chuo, Sagamihara, Kanagawa 252-5201 Japan 1-17-71 Fuhinobe, Chuo, Sagamihara, Kanagawa 252-5201 JapanBackground: Despite an initial favorable response to hypofractionated radiotherapy (RT), intranasal neoplasia has a poor long-term prognosis. Re-irradiation (re-RT) has been shown to result in clinical remission in dogs with recurrent intranasal tumors. Hypofractionated re-RT is indicated in cases of recurrence. Aim: This study aimed to investigate the response of patients with recurrent intranasal tumors who were initially treated with repeated hypofractionated RT. Methods: Medical records of dogs with intranasal tumors that relapsed after undergoing hypofractionated RT at Azabu University Veterinary Teaching Hospital and who underwent re-RT between 2008 and 2022 were retrospectively analyzed. Results: Among the 30 dogs included, 20 had adenocarcinomas. Eleven patients underwent second re-irradiation, and five patients underwent third re-irradiation. The median total isocenter dose and total number of fractions were 56 Gy (range, 37.5–102) and 8 fractions (range, 5–14), respectively. The first, second, and third progression-free intervals (PFI) were 315 (n = 30), 185 (n = 11), and 218 days (n = 4), respectively. Overall survival (OS) was 504 days (n = 30). Adverse events such as alopecia (n = 7), white hair (n = 8), cataracts (n = 9), pigmentation (n = 5), keratitis (n = 3), and corneal ulceration (n = 1) were limited to grades 1 and 2. The medians of the first PFI for one course and two or more courses of re-RT were 298 and 331 days, respectively, indicating no significant differences between the groups. The OS after two or more courses of re-RT (758 days) was significantly longer than after one course of re-RT alone (414 days) (P = 0.048). However, the cases were not randomized and most of the tumor types were adenocarcinomas. Conclusion: Since it is expected to prolong survival time with few life-threatening adverse events, the findings of the present study suggest that hypofractionated re-RT can be used in dogs with recurrent intranasal tumors initially treated with hypofractionated RT. Therefore, repeated hypofractionated re-RT may be a reasonable option for young dogs with a good initial response and recurrent intranasal tumors. [Open Vet J 2025; 15(2.000): 827-834]http://www.ejmanager.com/fulltextpdf.php?mno=226692doghypofractionated radiotherapyintranasal tumorrecurrencere-irradiation
spellingShingle Hirona Ueno
Yuta Nishiyama
Takuya Maruo
Yohei Fukuda
Takayuki Katayama
Shinichiro Yoda
Kotaro Nishi
Hideki Kayanuma
Clinical outcomes and prognostic factors of repeated conventional hypofractionated radiotherapy for recurrent intranasal tumors in dogs
Open Veterinary Journal
dog
hypofractionated radiotherapy
intranasal tumor
recurrence
re-irradiation
title Clinical outcomes and prognostic factors of repeated conventional hypofractionated radiotherapy for recurrent intranasal tumors in dogs
title_full Clinical outcomes and prognostic factors of repeated conventional hypofractionated radiotherapy for recurrent intranasal tumors in dogs
title_fullStr Clinical outcomes and prognostic factors of repeated conventional hypofractionated radiotherapy for recurrent intranasal tumors in dogs
title_full_unstemmed Clinical outcomes and prognostic factors of repeated conventional hypofractionated radiotherapy for recurrent intranasal tumors in dogs
title_short Clinical outcomes and prognostic factors of repeated conventional hypofractionated radiotherapy for recurrent intranasal tumors in dogs
title_sort clinical outcomes and prognostic factors of repeated conventional hypofractionated radiotherapy for recurrent intranasal tumors in dogs
topic dog
hypofractionated radiotherapy
intranasal tumor
recurrence
re-irradiation
url http://www.ejmanager.com/fulltextpdf.php?mno=226692
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