Immunohistochemical Expression and Prognostic Value of COX-2 and Alpha-Smooth Muscle Actin-positive Cancer-associated Fibroblasts in Feline Mammary Cancer.

Background: Cyclo-oxygenase-2 (COX-2) and cancer associated fibroblasts (CAFs) play an important role in the development and progression of tumor malignancy in humans and animals, showing that both can influence the tumor microenvironment. However, the impact of these two markers in feline mammary carcinogenesis has not yet been addressed. Materials and Methods: In the present study, the clinicopathological significance of COX-2 immunoexpression and alpha-smooth muscle actin (a-SMA)-positive cancerassociated fibroblasts (CAFs) was determined and correlated with disease-free and overall survival of 50 felines with malignant mammary tumors. Results: COX-2 overexpression was positively associated with mitotic index (p=0.031), degree of malignancy (p=0.001), lymph node metastasis (p=0.001), vascular invasion (p=0.002), disease recurrence (p=0.019) and distant metastasis (p=0.036). a-SMA-positive CAFs were associated with mitotic index (p=0.004), lymph node metastasis (p=0.027), vascular invasion (p=0.05), disease recurrence (p=0.001) and distant metastasis (p=0.001). Additionally, both markers were correlated with disease-free and overall survival, emerging as predictors of poor prognosis. Conclusion: Our results indicate for the first time that the presence of two markers, COX-2 and a-SMA, is associated with carcinogenesis and worse prognosis in feline mammary cancer and that a-SMA-positive CAFs have a role in feline mammary tumorigenesis, cancer development, and clinical outcome. [ABSTRACT FROM AUTHOR]