Evaluation of serum CA15-3, CEA, Ki-67, PDL-1 and VEGF as a potential diagnostic and prognostic biomarkers in canine mammary tumors

Canine mammary tumors are the most common tumor type among all cancer types. The study aims to evaluate the presence of tumor and early metastasis by comparing CEA, CA15-3, Ki-67, VEGF, and PD-L1 profiles in canine mammary tumors with and without metastasis and in healthy dogs, and to understand the effectiveness of the parameters in tumor diagnosis and prognosis. Female dogs with mammary tumors were divided into two groups as metastatic (n = 20) and non-metastatic (n = 20) according to anamnesis, physical examination, blood analysis, imaging methods, and histopathology. Dogs without active complaints and applied to the clinic with a request for routine neutering constituted the healthy group (n = 20). Serum samples were taken from dogs in all groups, and serum CA15-3, CEA, VEGF, Ki67, and PD-L1 levels were measured with ELISA. The levels of CEA and CA15-3 were significantly higher in the serum of dogs with mammary tumors (metastatic and non-metastatic) compared to healthy ones. Serum VEGF levels were found to be highest in dogs with metastatic mammary tumors. Dogs with non-metastatic mammary tumors were found to exhibit the highest serum levels of Ki-67. There were no significant differences in PD-L1 among groups. A strong positive correlation was detected between all serum parameters. CEA, CA15-3, VEGF, and Ki-67 could be a useful diagnostic tool for canine mammary tumors with the AUC values of 0.770, 0.693, 0.696, and 0.902, respectively. In addition, Ki-67 was the best predictor of metastasis in dogs with mammary tumors, with an AUC value of 0.902. In conclusion, serum CEA, CA15-3, VEGF, and Ki-67 parameters can be applied to increase the efficiency of diagnosis and prognosis evaluation in canine mammary tumors.