The role of Cox-2 expression in the prognosis of dogs with malignant mammary tumours

Immunohistochemical detection of Cyclooxygenase (Cox)-1 and -2 enzymes in canine mammary tumours (CMT) has recently been described. However, the prognostic value of their expression needs to be established. The aim of this study was to investigate Cox (-1 and -2) prognostic value in malignant CMT by evaluating its correlation with clinicopathological parameters (tumour size, histological type, necrosis, lymph node metastasis) and with Disease Free Survival (DFS) and Overall Survival (OS). Twenty seven female dogs with malignant tumours were included. Cox-2 expression was associated with lymph node metastasis at surgery time, development of distant metastasis during follow-up (p = 0.038), DFS (p = 0.03) and OS (p = 0.04). Multivariate survival analysis showed that Cox-2 did not retain its significance as an independent prognostic factor. For Cox-1 expression, no statistically significant association was observed. Present study suggests the usefulness of testing Cox-2 specific inhibitors as part of an adjuvant therapy in female dogs with malignant mammary neoplasias.