Cyclooxygenase-2 Expression in Invasive Breast Carcinomas of No Special Type and Correlation with Pathological Profiles Suggest a Role in Tumorigenesis Rather than Cancer Progression

Background: COX-2 has been shown to play an important role in the development of breast cancer andincreased expression has been mooted as a poor prognostic factor. The purpose of this study was to investigatethe relationship between COX-2 immunohistochemical expression and known predictive and prognostic factorsin breast cancer in a routine diagnostic histopathology setting. Materials and
Methods: Formalin-fixed paraffinembeddedtumour tissue of 144 no special type (NST) invasive breast carcinomas histologically diagnosed betweenJanuary 2009 and December 2012 in Hospital Sultanah Bahiyah, Alor Setar, Kedah were immunostained withCOX-2 antibody. COX-2 overexpression was analysed against demographic data, hormone receptor status, HER2-neu overexpression, histological grade, tumour size and lymph node status.
Results: COX-2 was overexpressedin 108/144 (75%) tumours and was significantly more prevalent (87%) in hormone receptor-positive tumours.There was no correlation between COX-2 overexpression and HER2/neu status. Triple negative cancers had thelowest prevalence (46%) (p<0.05). A rising trend of COX-2 overexpression with increasing age was observed.There was a significant inverse relationship with tumour grade (p<0.05), prevalences being 94%, 83% and66% in grades 1, 2 and 3 tumours, respectively. A higher prevalence of COX-2 overexpression in smaller sizetumours was observed but this did not reach statistical significance. There was no relationship between COX-2expression and lymph node status.
Conclusions: This study did not support the generally held notion that COX-2overexpression is linked to poor prognosis, rather supporting a role in tumorigenesis. Larger scale studies withoutcome data and basic studies on cancer pathogenetic pathways will be required to cast further light on whetherCOX-2 inhibitors would have clinical utility in cancer prevention or blockage of cancer progression. In eithersetting, the pathological assessment for COX-2 overexpression in breast cancers would have an important rolein the selection of cancer patients for personalized therapy with COX-2 inhibitors.