A combined protocol with piroxicam, chemotherapy and whole pelvic irradiation with simultaneous boost volumetric modulated arc radiotherapy for muscle-invasive canine urinary transitional cell carcinoma: first clinical experiences

The aims of this pilot study were to evaluate the feasibility and efficacy of high-dose hypo-fractionated volumetric modulated arc radiotherapy (VMAT) applied to the whole pelvic region radiotherapy (WPRT) with multilevel simultaneous integrated boost (MLSIB) combined with piroxicam and chemotherapy in canine transitional cell carcinoma (TCC) of the lower urinary tract with muscle invasion transitional cell carcinoma (TCC). Twelve dogs were enrolled, according to stage, in two groups: group 1, TCC confined to the urinary tract; group 2, TCC with metastasis. The planning target volume (PTV-tumor) dose was tailored from 36 to 42 Gy in 6 fractions. All dogs were prescribed piroxicam and radiosensitizing carboplatin and six received chemotherapy after radiotherapy. Serial follow-up with computed tomography (CT) and magnetic resonance imaging (MRI) examinations was performed. Disease control and toxicity effects were evaluated according to the Response Evaluation Criteria in Solid Tumor (RECIST) and Veterinary Radiation Therapy Oncology Group (VRTOG) criteria. The treatment was well tolerated, and no high-grade side effects were reported. The median overall survival times for group 1 and group 2 were 1,230 days and 150 days, respectively. A considerable percentage of patients in group 1 (50%) was still alive at the time of writing, and a longer follow-up could enable a more accurate survival analysis. This preliminary analysis showed that VMAT applied to the WPRT with MLSIB is an effective and safe option for dogs suffering from lower urinary TCC although the presence of metastases worsens the prognosis

Volumetric Modulated Arc (Radio) Therapy in Pets Treatment: The “La Cittadina Fondazione” Experience

Volumetric Modulated Arc Therapy (VMAT) is a modern technique, widely used in human radiotherapy, which allows a high dose to be delivered to tumor volumes and low doses to the surrounding organs at risk (OAR). Veterinary clinics takes advantage of this feature due to the small target volumes and distances between the target and the OAR. Sparing the OAR permits dose escalation, and hypofractionation regimens reduce the number of treatment sessions with a simpler manageability in the veterinary field. Multimodal volumes definition is mandatory for the small volumes involved and a positioning device precisely reproducible with a setup confirmation is needed before each session for avoiding missing the target. Additionally, the elaborate treatment plan must pursue hard constraints and objectives, and its feasibility must be evaluated with a per patient quality control. The aim of this work is to report results with regard to brain meningiomas and gliomas, trigeminal nerve tumors, brachial plexus tumors, adrenal tumors with vascular invasion and rabbit thymomas, in comparison with literature to determine if VMAT is a safe and viable alternative to surgery or chemotherapy alone, or as an adjuvant therapy in pets

A Combined Hypofractionated Volumetric Modulated Arc Radiotherapy, Radio-Sensitising and Adjuvant Metronomic Chemotherapy Treatment for Canine Stage IV Nasal Tumours With Intracranial Extension

Radiation therapy has become the standard of care in the treatment of canine intranasal neoplasia, but because of the poor prognosis associated with stage IV nasal tumours and the proximity of the brain to the irradiation target, few data regarding the treatment of very advanced neoplasms are available. The aim of this pilot study was to evaluate the feasibility, safety and effectiveness of a combined treatment composed of definitive high-dose hypofractionated volumetric modulated arc radiotherapy on tumours with concurrent treatment of regional lymph nodes if positive or as prophylaxis, carboplatin radio-sensitising, and adjuvant metronomic chemotherapy for stage IV canine nasal tumours with intracranial extension. A pilot observational study was conducted in 7 dogs. Magnetic resonance imaging follow-up examinations revealed complete responses in 5 dogs and partial responses in 2. The median overall survival time, evaluated via Kaplan-Meier survival analysis, was 310 days with a 95% confidence interval of 210-400 days, whereas the median progression-free survival was 240 days with a 95% confidence interval of 190-290 days. Despite the proximity of highly sensitive organs at risk, no grade III or IV toxicities were observed, and volumetric modulated arc radiotherapy seemed to be a feasible treatment option for stage IV canine nasal tumours where conformal 3D radiotherapy has proven to give higher doses with severe damage to the surrounding unaffected tissues. Further studies are needed on the role of the sphenoid bone microscopic infiltration and regional lymph node involvement. The absence of severe toxicity could also lead to a dose escalation study and chemotherapy scheme

Cranial Spinal Spreading of Canine Brain Gliomas after Hypofractionated Volumetric-Modulated Arc Radiotherapy and Concomitant Temozolomide Chemotherapy: A Four-Case Report

Gliomas are the second-most-common primary brain tumors in dogs. Surgery and radiotherapy are established treatment approaches with similar median survival time, whereas conventional chemotherapy is burdened by severe adverse effects. Spinal and leptomeningeal spread of gliomas have been described following radiotherapy treatment alone. The purpose of this study was to evaluate the outcome for four dogs with primary high-grade gliomas in the forebrain without evidence, at diagnosis, of neoplastic invasion along the spinal cord, that were treated with concomitant chemotherapy (temozolomide) and hypofractionated volumetric-modulated arc radiotherapy (VMAT-RT). Temozolomide was selected for its radiosensitive properties, and radiotherapy dose protocols of 37 Gy in 7 fractions or 42 Gy in 10 fractions were used. After an initial complete or partial response, tumors recurred across the cranial–spinal pathway. Post-mortem macroscopic examinations confirmed swollen spinal cord and hyperemic meningeal sleeve, with nodular lesions on the meningeal surface. Microscopically, infiltration of the spinal cord and meninges by neoplastic cells (with features of oligodendrogliomas) were observed. This work seems to suggest that the entire central nervous system should be investigated in diagnostic examinations of canine gliomas. Dose-escalation trials and/or spinal cord prophylaxis treatment could also be evaluated to prevent tumor progression