Frameless stereotactic radiotherapy alone and combined with temozolomide for presumed canine gliomas

Abstract

We evaluated stereotactic volume modulated arc radiotherapy (VMAT) for canine gliomas, alone (radiotherapy [RT]) and in combination with temozolomide (RT + TMZ), compared with palliation. Overall and disease-specific survival times were estimated. Thirty dogs were palliated, 22 dogs were treated with RT and 20 with RT + TMZ. Complete and partial responses were observed in 63.2% and 90.9% of patients in the RT and RT + TMZ arms, respectively, that were alive at 1 year. Median survival in the palliation arm was 94 days (95% conformity index [CI] 87÷101). Median survivals of the RT arm (383 days, 95% CI 276÷490) and RT+TMZ arm (420 days, 95% CI 280÷560) were not significantly different (P = .61). Positive correlation with survival was found both for the ratio between target and brain (relative) volume of the tumour of <5% (P = .013) and for a clinical presentation with normal mentation (P = .032). VMAT is feasible and effective for canine brain gliomas. Combining this therapy with TMZ did not elicit any additional improvement in survival time.

High dose hypofractionated frameless volumetric modulated arc radiotherapy is a feasible method for treating canine trigeminal nerve sheath tumors

“…Animals were positioned in sternal recumbency in a wooden cradle containing a vacuum mattress. A bite block made of polymethylmethacrylate fitting the upper dentition was used . The CT origin coordinates were aligned to the cradle with the CT positioning lasers.…”

“…), lesions of complex shape affecting critical neural structures near to organs at risk can now be successfully addressed with potential advantages over past treatment modalities . In particular, volumetric modulated arc radiotherapy, which is a form of dynamic IMRT, has been successfully used in veterinary medicine for the treatment of brachial plexus tumors, presumed gliomas, rabbit thymomas, canine adrenocortical tumors, intracranial meningiomas, and carotid paraganglioma …”

Residual setup error in the canine intracranial region after megavoltage, kilovoltage, or cone‐beam computed tomographic image guidance for radiation therapy

“…When stereotactic radiation therapy (SRT) and stereotactic radiosurgery (SRS) are used to treat intracranial tumours, a small PTV expansion is desirable as normal tissues adjacent to the tumour are spared by avoidance, rather than fractionation. The PTV reported for canine patients with brain tumours treated with SRT and SRS in a variety of immobilization systems ranges from 0 to 3 mm . On‐board image guidance or portal imaging were used in these studies to minimize setup error.…”

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

“…These brain radiation therapy protocols involve either weeks of treatments and/or large regions of normal brain receiving high radiation dose, total doses of 45–54 Gray (Gy) with 2.5‐3 Gy given in multiple fractions, or palliative protocols with weekly doses of 5–9 Gy . Although chemotherapy has been used with some intracranial tumors, a survival benefit has not clearly been demonstrated, including for pituitary masses . The potential benefits of stereotactic radiotherapy for a variety of intracranial tumor types in dogs have previously been described, but pituitary tumors have accounted for very few stereotactic radiotherapy patients in the literature …”

“…Although chemotherapy has been used with some intracranial tumors, a survival benefit has not clearly been demonstrated, including for pituitary masses . The potential benefits of stereotactic radiotherapy for a variety of intracranial tumor types in dogs have previously been described, but pituitary tumors have accounted for very few stereotactic radiotherapy patients in the literature …”