Solitary intraventricular tumors in dogs and cats treated with radiotherapy alone or combined with ventriculoperitoneal shunts: A retrospective descriptive case series

Abstract

Background Intraventricular tumors are rare, optimal treatment is not defined. Symptomatic patients often exhibit life‐threatening hydrocephalus. With several months time‐to‐effect after radiotherapy (RT), increased intracranial pressure is concerning. This increase in pressure can be overcome by ventriculoperitoneal shunting (VPS). Objectives Retrospective evaluation of outcome and complications in dogs and cats with intracranial tumors treated with either RT or VPS/RT. Animals Twelve client‐owned cats and dogs. Methods Dogs and cats with symptomatic intraventricular tumors treated with definitive‐intent RT or VPS/RT were included in a retrospective, descriptive case series. Complications, tumor volume evolution, time‐to‐progression, and survival time were determined. Results Twelve animals were included: 1 cat and 5 dogs treated with single‐modality RT and 4 cats and 2 dogs treated with VPS/RT. Neurological worsening seen in 4/6 animals during single‐modality RT and 2/6 died during RT (suspected brain herniation). All dogs with VPS normalized clinically by the end of RT or earlier. Complications occurred in 4/6 animals, all but 1 were successfully managed surgically. Imaging follow‐up in 8 animals surviving RT showed a marked decrease in tumor volume. Median survival time was 162 days (95% confidence interval [CI]: 16; infinity) for animals treated with RT and 1103 days (95%CI: 752; infinity) for animals treated with VPS/RT. Median time‐to‐progression was 71 days (95%CI: 7; infinity) and 895 days (95%CI: 704; infinity) for each group, respectively. Two dogs died because of intraventricular metastasis 427 and 461 days after single‐modality RT. Conclusions and Clinical Importance Ventriculoperitoneal shunting led to rapid normalization of neurological signs and RT had a measurable effect on tumor volume. Combination of VPS/RT seems to be beneficial.

Stereotactic radiotherapy outcomes for intraventricular brain tumours in 11 dogs

“…There were three dogs with surgery prior to SRT (OS 406 days) and the remainder received For some dogs with intraventricular tumours, decompensation secondary to obstructive hydrocephalus occurs and can be life-threatening. 17 In this cohort, 4/11 dogs had 3D-imaging descriptions of moderate to marked ventricular enlargement; the ventricles were diffusely enlarged in two dogs, while only the third or lateral ventricle was enlarged in the other two dogs. Importantly, these four dogs had the shortest survival time ranging from 24 to 113 days.…”

“…For some dogs with intraventricular tumours, decompensation secondary to obstructive hydrocephalus occurs and can be life‐threatening 17 . In this cohort, 4/11 dogs had 3D‐imaging descriptions of moderate to marked ventricular enlargement; the ventricles were diffusely enlarged in two dogs, while only the third or lateral ventricle was enlarged in the other two dogs.…”

“…The presence of ventriculomegaly was not always associated with a shorter survival, as the four longest surviving dogs (953–2072 days) all had one ventricle dilated (lateral (2), third (1), and fourth (1)). Given the dynamic obstructions caused by ventricular tumours, surgical shunts to improve intracranial pressure may be warranted, and has been recently reported with fractionated radiotherapy and a mixed‐species population 17 . However, potential complications of CSF‐shunting in dogs with intraventricular exfoliating cancers, and whether abdominal tumour seeding is clinically relevant compared to the acute brain signs, is not fully understood.…”

“…Dogs received 40–50 Gy (4–4.5 Gy × 10 or 2.5 Gy × 20 fractions), and survival times with a shunt were significantly longer (overall survival time [OS] 36.3 months, including two dogs) than those with radiotherapy alone (OS 5.3 months, including five dogs). In that study, two dogs without shunts died during the radiotherapy course 17 …”

“…In that study, two dogs without shunts died during the radiotherapy course. 17 Access to on-board imaging (OBI), cone-beam computed tomography (CBCT), and intensity-modulated radiotherapy (IMRT) have improved radiation delivery, providing the ability to deliver stereotactic radiotherapy (SRT) in high-dose treatments delivered in just 1-5 fractions, and sparing normal tissues by avoidance. 16,18,19 Intraventricular tumours are intra-cranial and thus have limited motion, and have somewhat well-defined edges within the ventricle providing for a more focused target.…”