High COX ‐2 expression is associated with increased angiogenesis, proliferation and tumoural inflammatory infiltrate in canine malignant mammary tumours: a multivariate survival study

COX ‐2 expression affects mammary tumourigenesis by promoting angiogenesis and cell proliferation, encouraging metastatic spread and tumour‐associated inflammation. Samples of canine mammary tumours ( n  = 109) were submitted to immunohistochemistry to detect COX ‐2, CD31 , VEGF , Ki‐67, CD3 and MAC387 expression. Concurrent high expression of COX ‐2/ CD31 , COX ‐2/ VEGF , COX ‐2/Ki‐67, COX ‐2/ CD3 and COX ‐2/ MAC was associated with elevated grade of malignancy, presence of intravascular emboli and presence of lymph node metastasis. Tumours with high COX ‐2 ( P  < 0.001) and tumours with concurrent expression of high COX ‐2 and high CD31 ( P  = 0.008); high VEGF ( P  < 0.001); high Ki‐67 ( P  < 0.001); high CD3 + T‐lymphocytes ( P  = 0.002) and elevated MAC387 macrophages ( P  = 0.024) were associated with shorter overall survival ( OS ) time. Interestingly the groups with high COX ‐2/ CD31 and high COX ‐2/ VEGF retained their significance after multivariate analysis arising as independent predictors of OS . Present data highlight the importance of COX ‐2 in canine mammary tumourigenesis.