Note: Unfortunately Science only allows a peek into it. Feel free to click "summary" in both.
(a) Table of Contents. Science, 347: 78-81 (Jan 2, 2015). www.sciencemag.org/content/347/6217.toc
The "toc" in the URL stands for "Table of Contents."
Two sections--and its respective pertinent articles.
(i) In Depth:
Jennifer Couzin-Frankel, The Bad Luck of Cancer
("Bert Vogelstein and Cristian Tomasetti of Johns Hopkins University have put forth a mathematical analysis of the genesis of cancer that suggests many cases are not preventable")
Take notice it is "mathematical" analysis. In a word, it is more or less like Einstein's theories, yet to be proved with experiments (biological, chemical or physical).
Something like "In Depth" (this is a new name for the section) used to be free, aimed for the public (as opposed to biologists), and written by a staffer (likely with a bachelor's degree, not PhD). Indeed, Ms Jennifer Couzin-Frankel "has been a staff writer for Science since 2002," according to Science.
(ii) The Report:
Cristian Tomasetti and Bert Vogelstein, Variation in Cancer Risk Among Tissues Can Be Explained by the Number of Stem Cell Divisions. .
The summary that Science proffers in the Web page of this URL: "Errors arising by chance during normal stem cell division explain more cancers than do hereditary or environmental factors."