Does a better grade of tumour occurring in women under hormone replacement therapy compensate for their lower probability of detection by screening mammography

Objective: To compare the prognostic factor of breast cancer survival between breast cancer diagnosed in subjects receiving hormone replacement therapy (HRT) before diagnosis to those without such a therapy. Subjects and methods: All breast cancers diagnosed between 1993 and 2000 within the breast cancer screening programme in Bouches do Rhone (France) were analysed for size, node status, and grade according to use, or not, of HRT. Univariate and multivariate analyses were carried out taking into account age, density of the breast, and mode of detection. Results: The breast tumours diagnosed among HRT users had a lower grade whatever the mode of detection. The proportion of node positive tumours was identical in the two groups after adjustment for age. The smaller size of the tumours among HRT users is partly explained by the lower grade of these tumours Conclusion: Although tumours occurring in HRT users have a lower chance of being detected by screening, their prognostic factors, especially the grade of the tumour, are better than in non-users. More work is needed to find which part of this advantage is attributable to better surveillance of women treated with HRT.