[Reproducibility of histoprognostic grades of invasive breast cancer]

In the framework of the quality assurance of the pathologists involved in the screening campaign it was proposed to test the reproducibility of the classical SCARFF, BLOOM and RICHARDSON (SBR) grade and the ELSTON-ELLIS grade (E-E) mentioned in the recent European recommendations. Twenty-four cases of invasive carcinoma were analyzed by 21 pathologists. Sixty-eight per cent agreement was obtained for the SBR grade and 69% for the E-E grade in the first round and vice versa in the second round. The mean value of the kappa test was 0.54 with SBR and 0.53 with E-E. The differentiation of the carcinoma was found to be the most reliable index (kappa score greater than 0.5), followed by the mitotic index (kappa score = 0.39 for SBR and 0.36 for E-E), and the nuclear polymorphism obtained the lowest score (kappa score ranging from 0.33 to 0.38). In our hands, the use of the E-E grade did not improve the reproducibility particularly for the mitotic index. Our results suggest however that the reproducibility may be improved by training.