Genomic tests show promise for early detection of canine cancers
For most dogs with cancer, the diagnosis confirms what the unexplained weight loss or lump under the skin suggests. At this stage, when signs of the disease are apparent, treatment is more difficult than if the cancer had been detected earlier.
One of the latest veterinary diagnostic tools with the potential to catch the leading pet dog killer is the liquid biopsy, or early detection test for multiple cancers. The test screens for genetic biomarkers, such as DNA damaged by cancer cells, in blood or other bodily fluids. As a screening test, an MCED test does not diagnose cancer, but a positive result suggests looking for the disease in the early stages when it may be more treatable.
“With most cancers, the more cells you have to kill with chemotherapy or radiation, or the bigger the tumor, the harder it becomes and the outcome is poorer,” said Dr. Kimberly Cronin, board-certified veterinary radiologist. in a reference firm in Boston.
“Detecting cancer at an early stage not only potentially makes treatment easier for a patient, but also has a huge impact on the human-animal bond,” Dr. Cronin said. “When it comes to cancer, most of our customers want to treat their pets the same way they would treat a human, within limits, of course.”
In April, the results of a clinical validation study of OncoK9, an MCED test for 30 types of canine cancer, were published in the online journal PLOS One. PetDx, the San Diego-based molecular diagnostics company that developed OncoK9, funded the CANcer Detection in Dogs – or CANDiD – study, involving 1,100 dogs of various breeds, weights and ages. The subjects were a mix of dogs diagnosed with cancer and dogs presumed to be cancer-free.
The study revealed that OncoK9 demonstrated a sensitivity of 54.7% and a specificity of 98.5%. For three of the most aggressive canine cancers (lymphoma, hemangiosarcoma and osteosarcoma), the detection rate was 85.4%. For eight of the most common canine cancers – lymphoma, hemangiosarcoma, osteosarcoma, soft tissue sarcoma, mast cell, mammary gland carcinoma, anal sac adenocarcinoma and malignant melanoma – the detection rate was 61.9%.
“One thing we decided early on to do as a company is to embed evidence-based medicine into everything we do, and this is the largest validation study ever in oncology diagnostics in veterinary medicine,” explained Dr. Andi Flory, a board-certified veterinary oncologist and PetDx’s chief medical officer. Dr. Flory added that the PLOS One study she oversaw aims to educate uncertain veterinarians about a type of cancer screening test that is relatively new to the fields of veterinary and human medicine.
“Vets are really scientists and data-driven people,” Dr. Flory said.
In addition to OncoK9, at least one other MCED test for dogs is currently available. The Texas A&M University College of Veterinary Medicine & Biomedical Sciences offers the Nu.Q Vet cancer screening test created by Volition, a biotechnology company based in Austin, Texas. Nu.Q tests blood for cancer biomarkers and claims a specificity rate of 97%. The test has been shown to detect 77% of lymphomas and 82% of hemangiosarcomas.
According to Dr. Cronin, screening tests such as OncoK9 and Nu.Q would be most effective when used on a yearly basis, especially in older dogs and breeds prone to cancer. One of the potential drawbacks is what happens if the screening test suggests the presence of cancer, but the cancer cannot be diagnosed with standard follow-up diagnostics.
“Then you are potentially left with a watch and wait approach, which is not something an owner would be comfortable with,” Dr. Cronin said.