Response: Methods for second primary cancers evaluation have to be standardized. Issue 6 (24th November 2017) - Chen, Tianhui; Brenner, Hermann; Fallah, Mahdi; Jansen, Lina; Castro, Felipe A.; Geiss, Karla; Holleczek, Bernd; Katalinic, Alexander; Luttmann, Sabine; Sundquist, Kristina; Ressing, Meike; Xu, Leiting; et al.