Long‐term survival with stereotactic radiotherapy for imaging‐diagnosed pituitary tumors in dogs

Abstract

Published studies on the use of stereotactic radiotherapy for dogs with pituitary tumors are limited. This retrospective observational study describes results of stereotactic radiotherapy for 45 dogs with imaging-diagnosed pituitary tumors. All dogs were treated at a single hospital during the period of December 2009-2015. The stereotactic radiotherapy was delivered in one 15 Gray (Gy) fraction or in three 8 Gy fractions. At the time of analysis, 41 dogs were deceased.Four were alive and censored from all survival analyses; one dog received 8 Gy every other day and was removed from protocol analyses. The median overall survival from first treatment was 311 days (95% confidence interval 226-410 days [range 1-2134 days]). Thirty-two dogs received 15 Gy (median overall survival 311 days; 95% confidence interval [range 221-427 days]), and 12 received 24 Gy on three consecutive days (median overall survival 245 days, 95% confidence interval [range 2-626 days]). Twenty-nine dogs had hyperadrenocorticism (median overall survival 245 days), while 16 had nonfunctional masses (median overall survival 626 days). Clinical improvement was reported in 37/45 cases. Presumptive signs of acute adverse effects within 4 months of stereotactic radiotherapy were noted in 10/45, and most had improvement spontaneously or with steroids. Late effects versus tumor progression were not discernable, but posttreatment blindness (2), hypernatremia (2), and progressive neurological signs (31) were reported.There was no statistical difference in median overall survival for different protocols. Patients with nonfunctional masses had longer median overall survival than those with hyperadrenocorticism (P = 0.0003). Survival outcomes with stereotactic radiotherapy were shorter than those previously reported with definitive radiation, especially for dogs with hyperadrenocorticism. K E Y W O R D SCushing's disease, hyperadrenocorticism, photon therapy, SRS, stereotaxis three-dimensional-conformal fields, or with a cone-based system for beam collimation. 17,18,25 There is one study of 51 dogs with

Efficacy of frameless stereotactic radiotherapy for the treatment of presumptive canine intracranial gliomas: A retrospective analysis (2014‐2017)

“…The use of this hypo-fractionated form of RT, termed stereotactic radiation therapy (SRT), has been described for the treatment of various intracranial neoplasms. [14][15][16][17][18][19] The major concern with increasing dose per fraction when irradiating brain tumours relates to the potential to cause late delayed brain injury. Typically, the ideal target for SRT has well-defined margins, thus lending itself well to a rapid drop off of radiation dose outside of the defined target volume.…”

“…Recent technological advances have allowed more precise and conformed delivery of RT, allowing for radical reductions in fraction number with an increase in dose per fraction. The use of this hypo‐fractionated form of RT, termed stereotactic radiation therapy (SRT), has been described for the treatment of various intracranial neoplasms 15–19 . The major concern with increasing dose per fraction when irradiating brain tumours relates to the potential to cause late delayed brain injury.…”

Treatment outcomes and target delineation utilizingCTandMRIin 13 dogs treated with a uniform stereotactic radiation therapy protocol (16 Gy single fraction) for pituitary masses: (2014‐2017)

“…Pituitary masses (PM) in dogs can result in clinical signs associated with endocrinopathies or neurologic dysfunction related to compression of the brain, brainstem and optic chiasm 1 . In most cases, radiation therapy (RT) is the primary treatment option because of the potential morbidity associated with hypophysectomy 2‐6 . The primary goal of RT is to stabilize and/or improve neurologic status, and delay or prevent progression of tumour growth.…”

Clinical features and their course of pituitary carcinoma with distant metastasis in a dog

“…Macroscopic pituitary tumors are common brain tumors in dogs, and compression of the surrounding normal brain tissue leads to various neurological symptoms [8,13]. To treat these tumors, megavoltage radiation therapy is currently used, and has resulted in a better prognosis [2,5,9,12,20]. Some macroscopic pituitary tumors are hormonally functional and produce adrenocorticotropic hormone (ACTH), which may present clinically as pituitary-dependent hyperadrenocorticism (PDH).…”

“…Some macroscopic pituitary tumors are hormonally functional and produce adrenocorticotropic hormone (ACTH), which may present clinically as pituitary-dependent hyperadrenocorticism (PDH). Shorter survival times have been reported in ACTH-active cases compared with those of ACTH-negative cases [5]. To date, the general purpose of treatment for pituitary tumors in dogs has been to achieve local tumor control, and little attention has been paid to distant metastases.…”