A comprehensive review has examined the current state of liquid biopsy (LBx) for cancer detection in dogs, including its applications and limitations for hemangiosarcoma.
Liquid biopsy is the analysis of fluids such as blood, urine, or saliva to detect cancer biomarkers and circulating tumor cells.
Unlike tissue biopsy, which is invasive and carries risks of bleeding and infection, LBx is minimally invasive and can be repeated over time. In human oncology, LBx is already used for treatment selection, monitoring therapeutic response, and detecting recurrence.
The review identified several commercially available LBx tests relevant to canine cancer.
Volition Nu.Q is a blood test that detects nucleosomes shed by cancer cells into circulation. In a study of 662 dogs, Nu.Q detected 82% of hemangiosarcoma cases, 77% of lymphoma, and 54% of histiocytic sarcoma.
OncoTect is a urine test that uses C. elegans chemotaxis, nematodes are attracted to volatile organic compounds in urine from dogs with cancer. In an initial study of 48 cancer and 30 non-cancer samples, OncoTect achieved 83% sensitivity and 96% specificity, with subsequent validation reportedly showing similar performance for lymphoma, melanoma, hemangiosarcoma, and mast cell tumors. The specific molecules driving the nematode response have not yet been identified.
The authors also described a novel technology under development called Urine Molecular Fingerprinting (UMF). Using Raman spectroscopy to detect molecular patterns in urine associated with cancer, UMF achieved 92.7% overall accuracy, 94.0% sensitivity, and 90.5% specificity in a study of 89 healthy dogs, 100 dogs with cancer, and 16 dogs with non-cancer urinary disease. The technology is still being validated.
No currently available LBx assay has conclusively demonstrated early detection of subclinical disease in dogs or humans.
All LBx tests are intended to be used alongside clinical evaluation, imaging, and tissue biopsy, not as standalone diagnostics.
For HSA, the most realistic current application is monitoring, serial testing during treatment could theoretically detect recurrence earlier, though whether this translates to better outcomes has not been shown.
The authors conclude that LBx has the potential to improve outcomes for dogs with cancer when used in conjunction with other tests and evaluations, but translating successes from human oncology will require substantial resources to develop new and more effective therapies
