The feline mammary
carcinoma (FMC) is the third most common
tumor in cat, sharing many clinicopathological features with human
breast cancer and thus, considered a suitable model for comparative oncology. Due to its poor prognosis, further studies are required to improve the diagnostic accuracy and treatment of cats with spontaneous mammary
carcinoma. Recently, it was reported that the overexpression of stromal cell-derived factor-1 (SDF-1) has great value in human
breast cancer diagnosis, suggesting that diagnostic tools and
therapies targeting the SDF-1
ligand can improve the clinical outcome. In this study, we aimed to evaluate if serum SDF-1 levels can also be used as a
biomarker of mammary
carcinoma in cats and to analyze if serum SDF-1 levels are associated with clinicopathological features, linked to a specific FMC subtype or correlated with the
tumor expression of SDF-1 receptor, the
chemokine C-X-C motif receptor 4 (CXCR4). Results showed that cats with mammary
carcinoma had significantly higher serum SDF-1 levels than healthy controls (p=0.035) and ROC analysis revealed that the best cut-off value to differentiate sick from healthy animals was 2 ng/ml (specificity: 80%; sensitivity: 57%; AUC=0.715). Significant associations were also found between cats with elevated serum SDF-1 concentrations (≥ 2 ng/ml) and HER2-overexpressing mammary
carcinomas (
Luminal B-like and HER2-positive subtypes, p<0.0001), CXCR4-negative mammary
carcinomas (p=0.027), mammary
carcinomas with small size (<3 cm, p=0.027) and
tumors with low Ki-67 expression (p=0.012). No statistical associations were found between serum SDF-1 levels and overall or disease-free survival. In summary, our results show that serum SDF-1 levels can be used as a
biomarker of feline mammary
carcinoma, especially in cats with HER2-overexpressing mammary
tumors. Data suggest that targeted
therapies against the SDF-1
ligand and/or its CXC4 receptor may be effective for the treatment of FMC, as described for human
breast cancer, strengthening the concept that spontaneous feline mammary
carcinoma is a suitable model for comparative oncology.