Response to the letter to the editor sent by J.M. Broeders and S. Moss on our article entitled 'Pitfalls in using case-control studies for the evaluation of the effectiveness of breast screening programmes' that appeared in the European Journal of Cancer Prevention, issue of 20 December 2012

We thank J.M. Broeders and S. Moss for their interest in our article (Autier and Boniol, 2012). J.M. Broeders and S. Moss have rightly understood the problem we raised that when breast cancer mortality decreases for reasons unrelated to screening, data used for computing are biased and systematically lead to overestimation of the screening ability to decrease the risk of breast cancer death in general populations (effectiveness).