The issue focused on two environmental factors that affect diet and cancer risk: vitamin D and cigarette smoking. There are many sources on this topic. All can be found at http://www.ncbi.nlm.nih.gov/pubmed/26436089

More details from this article (link here): http://www.ncbi.nlm.nih.gov/pubmed/26436089

Read more about evidence that tobacco smoking causes cancer at http://www.nc