My attention has been called to this correspondence. While fully aware of the importance of investigating the causes of cancer by all possible means, I am unable to undertake that the subject should be pursued in the manner proposed in the question, as there are insuperable difficulties in drawing accurate inferences from comparison of recorded cancer deaths rates in the different countries of the world. The question of international study of cancer prevalence is, however, receiving attention in my Department, and is being brought before the international bodies concerned with public health questions.