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.