Authors ’ Response to the letter to the editor: Cancer screening: inequalities... in the data

We would like to comment on the letter by Braillon1 related to our previous article published in this jour-nal.2 We agree with Braillon1 on the fact that the prevalence of screening showed in our study,2 which was derived from data provided by the World Health Survey,3 are not precise estimates. Data obtained by means of surveys may differ from those obtained from other sources (as e.g. data from organized pro-grammes), and one of the reasons is that biases may arise from self-reported data. However, we think that the main source of the difference is that they may not be measuring the same thing as we will try to argue below. We agree with the fact that mammography screen-ing within an organized programme is always the bes