During the past decade, research linking energy balance to the initiation, development, progression and treatment of cancer has grown substantially. Energy balance–related conditions and health behaviors, including overweight, obesity, physical inactivity, and poor diet have been linked to increased incidence of many cancers.1–4
Several estimates of population-attributable risk suggest excess body fat may account for 3%–9% of all cancers and one fifth to one third of postmenopausal breast, colon, endometrial, kidney, and digestive cancers.5–8
Associations between energy balance and related health behaviors and poor quality of life, recurrence and mortality have also been identified in cancer survivors.9–13
Such evidence is particularly important given that approximately two thirds of U.S. adults are overweight or obese,14
and physical inactivity,15
and poor diet17
As the principal federal funding agency of biomedical research in the U.S., the NIH, housed in the DHHS, supports more than 90% of obesity research in the country through its 27 institutes and centers.18
In 2003, the National Cancer Institute (NCI) formally identified energy balance as a strategic research area.19
The priorities in the plan were informed by the NCI Energy Balance Working Group, which convened staff across programs and divisions with an expertise in research on diet/nutrition, physical activity, and weight across the range of research areas represented in NCI-funded grants, including behavioral science, epidemiology, genomics, surveillance, and applied research. In 2005, the NIH created an agency-wide task force to accelerate progress in obesity research: the NIH Obesity Research Task Force (ORTF), which published the NIH obesity research strategic plan21
that was updated in 2011.20,22
Together these plans and reports illustrated the growing consensus around the importance of energy balance and chronic disease, including cancer, and the need for coordinated research. In its 2003 research priority statement, NCI defined energy balance as:
“the integrated effects of diet, physical activity, and genetics on growth and body weight and cancer related research that encompasses research over the life course, across the cancer continuum and across stages and phases of cancer from the level of the cell to that of policy.”19
Energy balance was described in this strategic document as four primary goals: discovery, surveillance, measurement, and intervention delivery. This definition and these elements of energy balance served as the basis of the criteria used in this portfolio analysis.
The discovery goal sought to foster research that integrated weight, physical activity, and diet, along with genetic and environmental factors, and the cancer development process through investment in basic, clinical and transdisciplinary research. The second goal, surveillance, focused on monitoring trends and determinants related to diet, physical activity, weight and related factors through collaboration with surveillance efforts across federal agencies and development of new survey instruments. The third, measurement, aimed to expand validation research, the development of electronic monitoring and web-based instruments and the identification of novel biomarkers. The last, intervention delivery, encouraged research related to planning, implementing and evaluating dietary and physical activity interventions. NCI’s energy-balance initiative addressed the need for research to broaden from a focus on cellular- and individual-level research to research on how the individual responds to the diverse social, environmental and physical environments that may either hinder or facilitate the adoption of recommended health behaviors.
Since then, substantial investments have been made in advancing energy-balance and cancer research in scope and complexity to enhance understanding of the underlying biological mechanisms as well as the influence of social–environmental and policy forces at the population level. In 2007, the World Cancer Research Fund advocated for research designs that emphasized dietary and lifestyle patterns and habits over individual nutrients or nutrient classes, indicating a shift from traditional perspectives on nutrition and cancer.1
In addition, new research has emerged on the benefits of physical activity in reducing recurrence and mortality and improving quality of life in cancer survivors.23,24
The 2011 NIH ORTF’s revised plan for obesity research calls for transdisciplinary approaches that integrate research on biologic mechanisms regulating energy balance with focus on disseminating, implementing and evaluating multilevel energy-balance interventions.22
NCI strategic planning and initiatives are consistent with many components of this new plan.
Given the evolution of the field and the growing prevalence of energy balance–related conditions and health behaviors, a review of the extramural grant portfolio for NCI, one of the leading funders of research on the topic, is timely. Earlier portfolio analyses of obesity research across the NIH have been performed, and they reflect the specific aspects of obesity treatment and intervention approaches as related to chronic disease prevention, but do not reflect specific energy balance– and cancer-related challenges that have recently emerged. This NCI portfolio analysis describes the growth of investigator-initiated research supported by NCI on energy balance–related conditions and behaviors over the past 7 years.