When cancer causation is at the heart of a toxic tort case it is critical to remain abreast of current research in the field. A good toxic tort lawyer must consider not only the science that will help him win his case, but also maintain an awareness of the scientific research related to basic knowledge about cancer causation, cancer prevention, and cancer treatments. This knowledge will ultimately translate into better openings, direct examinations, cross examinations, and closings.
Last month we addressed some trial-specific thinking, with a focus on a hypothetical case involving multiple co-factors involved in the development of one type of cancer in one hypothetical plaintiff. This month, in contrast, we present big picture context for thinking about how environmental “toxins” are related to the development of cancer. We will focus on the divergent sound bites that emerged in 2015 from two high impact studies.
In January 2015 a scientific article made headlines with the sound bite: “‘Bad luck’ of random mutations plays predominant role in cancer, study shows.” In December, a second study was published with quite a different set of headlines: 2015 headline and sound bite: “Cancer is not just ‘bad luck’ but down to environment, study suggests”
The two seemingly contradictory sets of headlines were generated by peer-reviewed papers in two highly respected journals (Nature and Science) from respected researchers working at respected institutions. And the second research project very explicitly followed up on the first project in order to further explore, and perhaps question, some tentative conclusions offered in the first project. So how should lawyers, clients, and juries hear, understand, and reconcile such apparently different conclusions? Clearly, it is critical to go beyond the headlines and put the messages in context by understanding some of the many reasons for asking big picture questions related to fundamental cancer research.
Thinking more about cancer prevention inevitably leads to more thinking about an age old question regarding chronic disease in general: nature vs. nurture? Since Darwin published his treatise, scientists have debated the relative importance of an individual’s innate qualities (the “nature” side of the equation) on the one hand and the competing role of his personal experiences (the “nurture” side of the equation) on the other. Researchers seeking cancer-specific answers to this broad debate generated the two, seemingly contradictory, papers that produced the sound bites and headlines.
The controversy starts with a January 2015 publication of a widely discussed and influential paper published in Science by Tomasetti and Vogelstein. After assimilating macro level research, they asserted that the vast majority of cancers were due to intrinsic factors (i.e., as opposed to extrinsic environmental factors). Specifically, the investigators assessed cancers occurring in different locations in the body and observed that they occurred at dramatically different frequencies. According to the authors, the million-fold difference between the most common and the least common cancers occurring in human cannot be explained by extrinsic factors such as exposure to carcinogenic substances. Rather, they attributed the vast difference in cancer frequency between tissues to the frequency of random errors occurring during cell division. In order to test their theory, the investigators correlated the number of stem cell divisions with the lifetime cancer risk for different tissue types. They found a high correlation between the number of cell divisions in a certain tissue type and the lifetime cancer risk for that tissue type. From these data, Tomasetti and Vogelstein offered the working conclusion that the majority of cancers lack environmental risk factors and that therefore they were due to “bad luck.”
Publication of the paper generated lots of press and controversy. Indeed, much has been written about whether or not the use of the phrase “bad luck” was appropriate (see here and here). Nevertheless, this study clearly highlighted the role of non-environmental factors in the induction of cancer.
The December 2015 paper published by Hu and colleagues in Nature explicitly followed up on the “bad luck” paper. This group of researchers, however, employed different macro level techniques to determine whether “cancer” (in general) is due to environmental factors or to “unlucky” cell replication. In contrast to the conclusions drawn by Tomasetti and Vogelstein, Hu and colleagues used four separate techniques to parse out what proportion of total cancer risk is due to extrinsic versus intrinsic factors. Each of their analyses supported the role of extrinsic environmental factors in the induction of cancer, and their working conclusion that intrinsic risk factors contribute only modestly (~ 10 – 30 percent) to cancer development. A recent interview with one of the study authors provides some interesting commentary on the topic, where he puts external risk factors into some appropriate context (pesticides, radiation from cell phones, smoking, etc.).
So, how do we reconcile these seemingly contradictory findings?
A head-to-head critique of the two papers is beyond the scope of this blog post. But, clearly, it is important to understand the big picture questions and potential answers in order to engage in the most useful thinking about the future of toxic tort litigation involving claims of carcinogenesis from external exposures. Obviously, even if you put stock in one study or the other, there is no clear-cut answer, yet. Tomasetti and Vogelstein conceded that external factors play a role and Wu and colleagues recognized that intrinsic factors are relevant. However, each set of investigators believes that their data support the view that the relative importance of these factors are the reverse of their adversaries).
Most importantly, these and other researchers will continue to ask broad questions, will examine their data, and will offer new interpretations and hypotheses (sometimes objectively and other times with investigator bias). Those developments will influence policymakers in their perceptions of, and thinking about, cancer causation and inevitably those outcomes will influence thinking about litigation involving cancer. Therefore, understanding the big picture is important, and persons involved in mass tort litigation can better avoid future surprises by understanding both the big picture hypotheses about cancer and the smaller picture, case-specific cancer hypotheses offered.
One step toward gaining a better understanding lies in a better appreciation of the related cost and treatment of cancers. Today, members of the US population are living far longer than did people in the 1960s and 1970s. Therefore, more cancers can and do arise because cancer risk increases with age. Another factor leading to more cancer is the large size of the cohort of people referred to as the baby boomers. On the other hand, the material decline in cigarette smoking is a major factor in the decline of the overall rate of cancer diagnoses. Early detection is another important factor in increasing survival.
Meanwhile, the media reports on a daily basis about increases in healthcare costs and debates about the value of drugs and other treatments that can mitigate cancer progression, but cannot “cure” cancer. With so much at stake, policy makers are asking researchers for more data and hypotheses about the most effective ways to prevent cancer. These concepts are addressed nicely in a very recent piece published in the American Association for Cancer Research Journal: Special Report on the Future of Cancer Prevention Research.
An overall takeaway? Public policy and knowledge regarding cancer are in periods of substantial analyses and re-analyses. It is useful for toxic tort stakeholders to develop a working knowledge of scientific advances that will help to shape future learnings related to cancer causation.
David H. Schwartz, Ph.D.
Kirk Hartley, Esq.