We would like to thank B. Faltas for his interest in our article. In our recent Science and Society article (Cancer: an old disease, a new disease or something in between? Nature Rev. Cancer 10, 728–733 (2010))1, we do not claim that cancer is entirely man-made, but rather that the high incidence of cancer in modern (that is, the late twentieth century and early twenty-first century) populations is significantly higher than that seen in the ancient Egyptian mummies we have studied. B. Faltas (Cancer is an ancient disease: the case for better palaeoepidemiological and molecular studies. Nature Rev. Cancer. 23 Dec 2010 (doi:10.1038/nrc2914-c1))2 refers to the Zink publications3,4, which are compared with an English population in the first 5 years of the twentieth century, which is not a comparable population, being well before the modern group to which we refer above and well before the explosion of cancer seen in that group, largely owing to an increase in tobacco usage, expansion of the petrochemical industry and increased radiation exposure.

Cancer certainly existed in antiquity, as noted in our paper, but the rarity of that diagnosis in the tens of thousands of skeletal remains and thousands of mummies that have been examined supports our view that most cancers in our modern populations are due to man-made factors.