Advancements in Veterinary Oncology—What You Need to Know

Improved Diagnostics

Traditional Diagnostic Imaging

For over 40 years, radiography and ultrasonography were routinely used to diagnose cancer in veterinary patients. These diagnostic imaging options were appealing to veterinary hospitals and clinics due to their comparative accessibility and low cost to operate. While these imaging techniques have some advantages, they are not extremely effective at detecting small, early-stage malignancies. As a result, veterinarians are making greater use of CT, MRI, and PET imaging modalities that can detect much smaller tumors and allow for improved tumor assessment capabilities using contrast agents. While these imaging techniques have a greater sensitivity for tumor detection, they are costly and require the use of anesthesia.

Liquid Biopsy Testing

Over the last several years, researchers have further developed their understanding of how changes in the genome cause cancer and a new “liquid biopsy” technique for detecting cancer has been developed. With liquid biopsy testing, a bodily fluid (usually blood, but urine, cerebrospinal fluid, or other secretions could be used) is obtained using a non-invasive or minimally invasive method. Most commonly, the sample is then analyzed to calculate the level of circulating tumor DNA (ctDNA)—which originates from cancer cells—that is present in the broader pool of cell-free DNA (cfDNA)—which is created due to normal cellular turnover. The presence of ctDNA is indicative of cancer, and further testing is then needed to provide a definitive diagnosis and determine the stage of the cancer. Liquid biopsy testing can be useful in all phases of cancer care, including:

• Screening for early detection, especially in high-risk patients.
• Assisting in the diagnosis process, particularly for tumors in difficult-to-access locations and tumors with an unknown location.
• Choosing targeted therapeutics for treatment.
• Checking treatment effectiveness.
• Monitoring for relapse.

Liquid biopsy testing is still being perfected, with developers focusing on improving test sensitivity to ensure cancer cases are accurately identified. In 2022, the CANcer Detection in Dogs (CANDiD) study, which included 1,100 dogs from 41 clinical sites worldwide, studied the sensitivity of liquid biopsy testing and found that it accurately detected:

• 85% of lymphoma, hemangiosarcoma, and osteosarcoma cases, which are the most aggressive of cancers found in dogs.
• 62% of the eight most common canine cancers—lymphoma, hemangiosarcoma, osteosarcoma, mast cell tumor, mammary gland carcinoma, soft tissue sarcoma, anal sac adenocarcinoma, and malignant melanoma.
• 55% for the twenty-two other cancers included in the study.

Liquid biopsy testing will not replace diagnostic imaging or solid biopsies, which require obtaining a portion of the tumor for testing but will complement them. In the future, liquid biopsy may enable veterinarians to detect cancer at the beginning stage of progression before changes are identifiable using diagnostic imaging, and it could play an important role in conducting multi-cancer early detection screens regularly in animals at high-risk for cancer, such as older dogs and breeds predisposed to cancer. Liquid biopsy testing is helpful for cases where a tumor sample is difficult to obtain and can also augment the information obtained from a solid biopsy. Tumors frequently contain cells with variations in genetic mutations both within separate sites of the same tumor and across tumors in different locations, and a liquid biopsy can detect this “tumor heterogeneity” more effectively than a solid biopsy. As a result, liquid biopsy testing will play a key role in providing patients with a personalized approach to treatment with targeted therapeutics.

Precision Medicine

Precision medicine, also referred to as personalized medicine, is shaping the trajectory of modern medicine, including veterinary oncology. With precision medicine, cancer biomarkers, including genes and proteins, are tested to provide critical information about a patient’s cancer. As a result, treatments are targeted to meet the patient’s unique needs, resulting in improved outcomes. For example, the analysis of the DNA of malignant tumors is advancing cancer management. Tumor profiling can be helpful in:

• Providing accurate diagnostic assessments.
• Making informed prognostic assessments.
• Guiding treatment plan development.
• Monitoring treatment effectiveness.

Biomarker testing is important in cancer care because the genetic mutations found in a cancerous tumor can vary significantly between patients, even if they have the same type of cancer. Additionally, the genetic mutations found within a particular tumor can change over time, and different tumors within the same patient may have different genetic mutations. These gene mutation variations can significantly impact standard cancer therapies’ effectiveness.

With tumor profiling, a core biopsy is done to obtain a tumor tissue sample. DNA from the tissue is then extracted and sequenced to identify the gene mutations present and to determine the proteins produced as a result of those specific mutations. The proteins driving the tumor’s growth can then be targeted with treatment options, including targeted drug therapy and immunotherapy. So, instead of killing all cells in the body that are growing and dividing rapidly as occurs with traditional chemotherapy, most targeted therapy attack only the proteins helping the tumor to grow and spread.