Response of Canine Soft Tissue Sarcoma to Stereotactic Body Radiotherapy

Stereotactic Radiation Therapy Planning, Dose Prescription and Delivery in Veterinary Medicine: A Systematic Review on Completeness of Reporting and Proposed Reporting Items

Increasing numbers of dogs and cats with cancer are treated with stereotactic radiosurgery, stereotactic radiation therapy or stereotactic body radiotherapy (SRS, SRT or SBRT). We provide a systematic review of the current data landscape with a focus on technical and dosimetric data of stereotactic radiotherapy in veterinary oncology. Original peer-reviewed articles on dogs and cats with cancer treated with SRT were included. The systematic search included Medline via PubMed and EMBASE. The study was performed according to the Preferred Reporting Items for Systematic Reviews (PRISMA) statement. We assessed the manuscripts regarding outcome reporting, treatment planning, dose prescription, -delivery and -reporting as well as quality assurance. As of February 2024, there are 80 peer-reviewed publications on various disease entities on SRS, SRT and SBRT in veterinary medicine. Overall, we found often insufficient or highly variable technical data, with incomplete information to reproduce these treatments. While in some instances, technical factors may not impact clinical outcome, the variability found in protocols, outcome and toxicity assessments precludes accurate and reliable conclusions for a benefit of stereotactic radiotherapy for many of the treated diseases. In line with the extensive recommendations from human stereotactic radiotherapy practise, we propose a draft of reporting items for future stereotactic radiation treatments in veterinary medicine. SRS, SRT and SBRT have specific clinical and technological requirements that differ from those of standard radiation therapy. Therefore, a deep understanding of the methodologies, as well as the quality and precision of dose delivery, is essential for effective clinical knowledge transfer.

Update in Veterinary Radiation Oncology: Focus on Stereotactic Radiation Therapy

Stereotactic radiotherapy (SRT) involves the precise delivery of highly conformal, dose-intense radiation to well-demarcated tumors. Special equipment and expertise are needed, and a unique biological mechanism distinguishes SRT from other forms of external beam radiotherapy. Families find the convenient schedules and minimal acute toxicity of SRT appealing. Common indications in veterinary oncology include nasal, brain, and bone tumors. Many other solid tumors can also be treated, including spinal, oral, lung, heart-base, liver, adrenal, and prostatic malignancies. Accessibility of SRT is improving, and new data are constantly emerging to define parameters for appropriate case selection, radiation dose prescription, and long-term follow-up.

A review of the development of histotripsy for extremity tumor ablation with a canine comparative oncology model to inform human treatments

Cancer is a devasting disease resulting in millions of deaths worldwide in both humans and companion animals, including dogs. Treatment of cancer is complex and challenging and therefore often multifaceted, as in the case of osteosarcoma (OS) and soft tissue sarcoma (STS). OS predominantly involves the appendicular skeleton and STS commonly develops in the extremities, resulting in treatment challenges due to the need to balance wide-margin resections to achieve local oncological control against the functional outcomes for the patient. To achieve wide tumor resection, invasive limb salvage surgery is often required, and the patient is at risk for numerous complications which can ultimately lead to impaired limb function and mobility. The advent of tumor ablation techniques offers the exciting potential of developing noninvasive or minimally invasive treatment options for extremity tumors. One promising innovative tumor ablation technique with strong potential to serve as a noninvasive limb salvage treatment for extremity tumor patients is histotripsy. Histotripsy is a novel, noninvasive, non-thermal, and non-ionizing focused ultrasound technique which uses controlled acoustic cavitation to mechanically disintegrate tissue with high precision. In this review, we present the ongoing development of histotripsy as a non-surgical alternative for extremity tumors and highlight the value of spontaneously occurring OS and STS in the pet dog as a comparative oncology research model to advance this field of histotripsy research.

Proposing Clinicopathological Staging and Mitotic Count as Prognostic Factors for Canine Soft Tissue Sarcomas

Soft tissue sarcomas (STSs) are a heterogeneous group of malignant mesenchymal tumors with similar histological features and biological behaviors. They are characterized by a low to moderate local recurrence rate and low metastasis, affecting approximately 20% of patients. Although this tumor set is vital in veterinary medicine, no previous unified staging system or mitotic count has been associated with patient prognosis. Therefore, this study proposed a new clinicopathological staging method and evaluated a cut-off value for mitosis related to the survival of dogs affected by STS. This study included 105 dogs affected by STS, treated only with surgery, and a complete follow-up evaluation. The new clinicopathological staging system evaluated tumor size (T), nodal involvement (N), distant metastasis (M), and histological grading criteria (G) to categorize the tumor stage into four groups (stages I, II, III, and IV). The proposed tumor staging system was able to differentiate patients' prognoses, with dogs with stage IV disease experiencing the lowest survival time and dogs with stage I disease having the highest survival time (p < 0.001). Moreover, we assessed the median mitosis (based on mitotic count) and its association with overall survival. Our study's median mitosis was 5, and patients with ≤5 mitoses had a higher survival time (p = 0.006). Overall, the proposed staging system and mitotic count seemed promising in the prediction of patient prognosis.

Age at cancer diagnosis by breed, weight, sex, and cancer type in a cohort of more than 3,000 dogs: Determining the optimal age to initiate cancer screening in canine patients

The goal of cancer screening is to detect disease at an early stage when treatment may be more effective. Cancer screening in dogs has relied upon annual physical examinations and routine laboratory tests, which are largely inadequate for detecting preclinical disease. With the introduction of non-invasive liquid biopsy cancer detection methods, the discussion is shifting from how to screen dogs for cancer to when to screen dogs for cancer. To address this question, we analyzed data from 3,452 cancer-diagnosed dogs to determine the age at which dogs of certain breeds and weights are typically diagnosed with cancer. In our study population, the median age at cancer diagnosis was 8.8 years, with males diagnosed at younger ages than females, and neutered dogs diagnosed at significantly later ages than intact dogs. Overall, weight was inversely correlated with age at cancer diagnosis, and purebred dogs were diagnosed at significantly younger ages than mixed-breed dogs. For breeds represented by ≥10 dogs, a breed-based median age at diagnosis was calculated. A weight-based linear regression model was developed to predict the median age at diagnosis for breeds represented by ≤10 dogs and for mixed-breed dogs. Our findings, combined with findings from previous studies which established a long duration of the preclinical phase of cancer development in dogs, suggest that it might be reasonable to consider annual cancer screening starting 2 years prior to the median age at cancer diagnosis for dogs of similar breed or weight. This logic would support a general recommendation to start cancer screening for all dogs at the age of 7, and as early as age 4 for breeds with a lower median age at cancer diagnosis, in order to increase the likelihood of early detection and treatment.

Cancer detection in clinical practice and using blood-based liquid biopsy: A retrospective audit of over 350 dogs

BACKGROUND

Guidelines-driven screening protocols for early cancer detection in dogs are lacking, and cancer often is detected at advanced stages.

HYPOTHESIS/OBJECTIVES

To examine how cancer typically is detected in dogs and whether the addition of a next-generation sequencing-based "liquid biopsy" test to a wellness visit has the potential to enhance cancer detection.

ANIMALS

Client-owned dogs with definitive cancer diagnoses enrolled in a clinical validation study for a novel blood-based multicancer early detection test.

METHODS

Retrospective medical record review was performed to establish the history and presenting complaint that ultimately led to a definitive cancer diagnosis. Blood samples were subjected to DNA extraction, library preparation, and next-generation sequencing. Sequencing data were analyzed using an internally developed bioinformatics pipeline to detect genomic alterations associated with the presence of cancer.

RESULTS

In an unselected cohort of 359 cancer-diagnosed dogs, 4% of cases were detected during a wellness visit, 8% were detected incidentally, and 88% were detected after the owner reported clinical signs suggestive of cancer. Liquid biopsy detected disease in 54.7% (95% confidence interval [CI], 49.5%-59.8%) of patients, including 32% of dogs with early-stage cancer, 48% of preclinical dogs, and 84% of dogs with advanced-stage disease.

CONCLUSIONS/CLINICAL IMPORTANCE

Most cases of cancer were diagnosed after the onset of clinical signs; only 4% of dogs had cancer detected using the current standard of care (i.e., wellness visit). Liquid biopsy has the potential to increase detection of cancer when added to a dog's wellness visit.