PTGS2 and ductal breast carcinoma in situ: In a multivariate analysis, higher cell-proliferation (P=0.006; Exp(B)1.034; 95% Confidence interval (CI) 1.01–1.06), higher nuclear-grade (P=0.003; Exp(B) 3.899; 95% CI 1.58–9.61) and higher COX-2 score (P=0.019; Exp(B) 1.632; 95% CI 1.09–2.46) were all independent predictors of increased recurrence of DCIS (also included in the analysis were surgical margin status (P=0.700), HER2 status (P=0.131) and age at diagnosis (P=0.419)).