The American Institute for Cancer Research (AICR) and the World Cancer Research Fund (WCRF) released a comprehensive new report on cancer prevention at the National Press Club in Washington, D.C. The report addresses cancer survivors as well as those who have not yet been diagnosed.
The new report, Diet, Nutrition, Physical Activity and Cancer: a Global Perspective, presents 10 evidence-based recommendations to lower cancer risk. The landmark report, which runs to thousands of pages, was also released at similar briefings held in London, Amsterdam, and Vienna, said Kelly Browning, CEO of the AICR. At the Washington briefing, Browning emphasized the "strong science behind these recommendations." He noted that they come at a time "when each individual scientific study seems to contradict a previous one," thus causing uncertainty and confusion and bolstering the need for scientific evidence.
The new report is the third in a series of comprehensive expert reports from the AICR/WCRF on diet, nutrition, physical activity, and cancer prevention; the others were released in 1997 and 2007.
Report Specifics
The 2018 report is based on analyses of global data from 51 million people, including 3.5 million cancer cases in 17 cancers. It states that between 30 percent to 50 percent of all cancer cases are estimated to be preventable through healthy lifestyles, along with avoidance of tobacco and exposure to occupational carcinogens, environmental pollutants, and certain long-term infections. The global cancer burden is projected to increase to 21.7 million new cases and 13 million deaths by 2030, primarily due to an aging population, states the report.
While the new third expert report affirms many of the recommendations of the previous two, such as avoiding weight gain, it also places new emphasis on certain issues, said speakers at the briefing. For example, the 2018 expert report recommends against drinking alcohol in any amount, stating: "For cancer prevention, it's best not to drink alcohol." The report also comes down hard on dietary supplements such as vitamins, stating, "Do not use supplements for cancer prevention." Nutritional needs should be met through diet alone, stresses the report.
Recognizing the growth in the number of cancer survivors due to advances in diagnosis and treatment, the new report stresses that they, too, should follow the recommendations for cancer prevention if they can, and they should receive advice on lifestyle issues such as diet and exercise from health care professionals. While conceding that there are gaps in research findings on survivors and cancer prevention, the report notes that following the recommendations can be important for long-term cancer survivors in preventing new primary cancers or other diseases with the passing years.
The report states that today "...cancer survivors are living long enough to develop new primary cancers or other non-communicable diseases." It adds, "For some cancers, especially those diagnosed at early stages (for example, prostate and breast cancer), cardiovascular disease will be a more common cause of death than cancer." Therefore, since the risks of diseases other than cancer are also modified by diet, nutrition, and physical activity, following the cancer prevention recommendations may also lower the risk of other non-communicable diseases.
Professional Feedback
Adopting the new report's recommendations provides a blueprint for cancer prevention, "a pattern to adopt, a habit to follow," emphasized Stephen D. Hursting, PhD, MPH, a member of the AICR/WCRF Continuous Update Project (CUP) panel that analyzes global data on how diet, nutrition, and physical activity affect cancer prevention; Professor in the Department of Nutrition and the Lineberger Comphrehensive Cancer Center at the University of North Carolina at Chapel Hill; and Professor at the UNC Nutrition Research Institute in Kannapolis. "It's uniquely comprehensive," Hursting said of the report's scope, at the Washington briefing.
"Over the years, the evidence has strengthened" on ways of preventing cancer, said Edward L. Giovannucci, MD, PhD, an AICR/WCRF CUP panel member and Professor in the Departments of Nutrition and Epidemiology at the Harvard TH Chan School of Public Health. Now "there are more studies and better studies," he said. For example, "the evidence is much stronger" now on avoiding alcohol to lower the risk of cancer. The dose-response seems to be linear. There is no safe level of consumption."
He also said the evidence against taking dietary supplements to prevent cancer is stronger. "A lot of supplements have been studied in great detail and the results have been disappointing." Hursting agreed: "The evidence isn't there that we can put something in a pill that will be protective," he said.
Like Browning, Giovannucci stressed that rigorous, evidence-based recommendations on cancer prevention are needed now more than ever, because "there's a lot of information out there and most of it is misinformation."
Speakers at the Washington briefing emphasized the importance of maintaining a normal weight throughout life to lower the risk of cancer. The report states that in 2016 globally an estimated 1.97 billion adults and more than 338 million children and adolescents were categorized as overweight or obese. The increase in the proportion of obese adults has been observed in low-income and middle-income countries, as well as in high-income countries. The 2018 expert report notes that obesity can increase the risk of cancer in multiple ways:
* it deregulates cellular energetics;
* it is linked to altered macrophage destruction, leading to the avoidance of immune destruction;
* it causes tumor-promoting inflammation;
* it leads to hyperinsulinemia; and
* it causes reduced apoptosis.
Guiding Patients
Asked by Oncology Times how oncologists should advise cancer survivors on lifestyle factors and cancer prevention, AICR Nutrition Adviser Karen Collins, MS, RDN, CDN, stressed that, in addition to following the new recommendations if possible, survivors should be receiving professional nutrition advice. But, she noted, "There are far too few cancer survivors who have access to nutritionists."
Agreeing was Elisa V. Bandera, MD, PhD, an AICR/WCRF CUP panel member and Professor at Rutgers University. She cited a report from the National Academy of Sciences that concluded that, even in comprehensive cancer centers, nutritionists might not be available. Given the increase in the number of long-term cancer survivors, "there is much more that we need to do in this area," said Bandera.
The third expert report emphasizes that future research directions should focus on studying the impact of diet, nutrition, and physical activity on outcomes in cancer survivors. It states: "There is emerging but still limited data on the effect of diet, nutrition, and physical activity in cancer survivors, regarding outcomes, including prognosis and quality of life during and after treatment."
Research is needed on dietary and lifestyle interventions specifically designed to address pre-defined outcomes; issues that may be unique to specific cancers, as well as the type of treatment and stage of disease; and increasing the knowledge base on the underlying biological mechanisms linking diet, nutrition, and physical activity to outcomes in cancer survivors.
Might cancer screenings provide a teachable, reachable moment on cancer prevention to intervene with people who are obese and/or have other factors that may increase risk? Also, might obese people need more frequent cancer screenings because of higher risk?
Asking these questions was briefing attendee Lisa Kennedy Sheldon, PhD, APRN, AOCNP, FAAN, Chief Clinical Officer of the Oncology Nursing Society. "Every time you touch a patient, every time you have an interaction provides an opportunity," replied Joanne Elena, PhD, MPH, Program Director in the Clinical and Translational Epidemiology Branch of the Epidemiology and Genomics Research Program, Division of Cancer Control and Population Sciences, at the NCI. Elena noted that currently "I don't think we have an answer" to tailoring screenings to cancer risk, but this is an active area of investigation at NCI.
Asked for further comment by Oncology Times, Sheldon noted that if an obese woman comes in for a screening mammogram, for example, it might provide an excellent opportunity to educate her on the benefits of losing weight to lower her risk of cancer. Sheldon said she has seen obese patients who developed breast cancer and then at a later time developed a second primary cancer, such as colon cancer.
Looking to the future, Hursting said there is going to be increasing precision of emerging research data on lifestyle interventions to lower the risk of cancer. For example, he said, it may turn out that, for some populations, consuming alcohol could be particularly detrimental. Thus, for these groups, following the expert report's recommendation to abstain from alcohol altogether may be especially important.
AICR has launched Cancer Health Check, a tool which allows consumers to see how their lifestyle stacks up against known cancer risks and outlines changes they can make to follow the new report's evidence-based cancer prevention recommendations. For further information, go to http://www.cancerhealthcheck.org.
Peggy Eastman is a contributing writer.
Future Research Directions
* Biological mechanisms by which diet, nutrition, and physical activity affect cancer processes
* The impact of diet, nutrition, and physical activity throughout the life course on cancer risk
* Better characterization of diet, nutrition, body composition, and physical activity exposures
* Better characterization of cancer-related outcomes
* Stronger evidence for the impact of diet, nutrition, and physical activity on outcomes in cancer survivors
* Globally representative research on specific exposures and cancer