A retrospective study was performed on archival paraffin-embedded formalin-fixed tissue samples of DCIS and MICB from women who had undergone surgery. The COX-2 expression was assayed by immunohistochemistry using a specific polyclonal anti-human COX-2 antibody. Expression was scored in a scale 0 (absent) to 4 (strong) based on the extent and intensity of tumour cell staining.
Fifty-two cases of DCIS and 40 of MICB were studied. In all cases, COX-2 was detected in the cytoplasm of tumour cells, and elevated COX-2 expression was observed in Van Nuys high-grade CDIS cases compared with low and intermediate grades (p < 0.05). In addition, enhanced COX-2 expression was significantly higher in DCIS component from MICB patients (82 % cases) than in DCIS pure patients (40.4 % ) (p < 0.05). In a multivariate model which includes age, tumour size, mammography, histological grade and COX-2 expression, we found COX-2 positivity to be an independent factor for microinvasion (OR 3.90; 95 % CI 1.88–14.3).
COX-2 is associated to higher Van Nuys grades of breast CDIS, and could be a molecular marker to identify the cases of DCIS which could progress to MICB.
COX-2 as a molecular marker in microinvasive carcinoma of the breast.