One of the first widely-reported cancer stories of 2015 was a widely publicized study in the journal Science which stated that “only a third of the variation in cancer risk among tissues is attributable to environmental factors or inherited predispositions.” The other two-thirds of cancer cases, argued Cristian Tomasetti and Bert Vogelstein of Johns Hopkins University, was due simply to “bad luck.”
In UndoCancer’s reporting of the Tomasetti-Vogelstein study on January 7, 2015, we expressed doubt about the authors’ conclusions. Now, a month later, a chorus of other researchers have weighed in on the matter. A few days after the Science article even lead author Tomasetti clarified, “We have not showed that two-thirds of cancer cases are about bad luck. Cancer is in general a combination of bad luck, bad environment and bad inherited genes.”
So who is to blame for all the headlines about “bad luck” causing most cancers? Professor George Davey-Smith,a clinical epidemiologist at Bristol University, argues that the study’s authors are to blame. The reference to “bad luck” was prominently used in the Science article’s abstract, as well as an accompanying editorial titled “The Bad Luck of Cancer.”
David Hunter, Harvard University’s Vincent L. Gregory Professor in Cancer Prevention, penned an op-ed in the Boston Globe on January 15 in which he took issue with the conclusions of Tomasetti and Vogelstein. Hunter wrote, “The vast majority of research does not show that cancer is the result of bad luck. Rather it shows that most cancers are theoretically preventable.”
Hunter points out that cancer rates vary dramatically within populations and between populations, and these differences can not be explained simply by genetic differences between races. In fact, in 1999, another set of Johns Hopkins researchers noted that Asian women who move to the United States, for example, see their breast cancer rates doubling within a decade. Breast cancer incidence is historically 4-7 times higher in the US than in Asia. Diet, tobacco use, hepatitis B, human papilloma virus, obesity, environment chemicals, radiation, and many other factors are all believed to play important roles in the incidence of cancers.
Tomasetti and Vogelstein, in the course of trying to actually write about why some types of cancer are more common than others, fell victim to the age-old temptation to make dramatic proclamations. The mainstream press should not be held accountable for reporting the specific language set forth in a peer-reviewed journal. And in the future, researchers will hopefully look back on this incident to further remind them to exercise moderation and clarity when explaining their results and ramifications.