Clinical Context

Cancer is one of the leading causes of morbidity and mortality worldwide, and the authors of the current recommendations provide a brief review of the global impact of cancer, as well as a glimpse into the expansion of cancer cases across the globe. At this time, cancer is responsible for 1 in 8 deaths across the globe, and wealthier countries bear the highest burden of cancer prevalence. By 2030, the global cancer burden is estimated to be 21.7 million new cases, with 13 million deaths resulting from cancer. The total economic cost of cancer worldwide in 2030 is estimated to be $458 billion.

The general aging of the population will increase the gross number of cancer cases in the near future, but more patients will also be surviving after the diagnosis and treatment of cancer. This is in no small part a result of efforts to detect cancer at earlier stages. There is also a new focus on the prevention of cancer, and the World Cancer Research Fund and American Institute for Cancer Research (AICR) have updated their lifestyle recommendations to prevent cancer.

Study Synopsis and Perspective

A new report that has reviewed all the data from the last 30 years on diet, weight, physical activity, and cancer has confirmed the link between cancer and lifestyle and provides evidence-based recommendations on how to reduce cancer risk.

The report distills the entirety of the literature down to 10 cancer prevention recommendations, said coauthor Nigel Brockton, PhD, director of research at the AICR.

"Each of these recommendations is based on factors for which there is strong evidence for increasing or decreasing risk of cancer, and they form a blueprint for healthy living to reduce the risk of cancer," Dr Brockton told Medscape Medical News.

Produced by the AICR and the World Cancer Research Fund, the new report is the third in a series. It reviews data from 51 million people, including 3.5 million cancer cases across 17 cancer sites.

It confirms recent results from a new study published in The Lancet Diabetes and Endocrinology that concludes being overweight (or obesity) is a cause of at least 12 cancers, as follows: liver, ovarian, prostate (advanced), stomach (cardia), oropharyngeal, colorectal, breast (postmenopausal), gallbladder, kidney, esophageal adenocarcinoma, pancreatic, and endometrial.

The third expert report, Diet, Nutrition, Physical Activity, and Cancer: A Global Perspective, updates the 2 previous comprehensive reports, which were published in 1997 and 2007.

Dr Brockton emphasized that the evidence in the current report is stronger than ever, but is "remarkably consistent" with the recommendations from the previous 2 papers. "The new report is based on much higher-quality data, mainly from prospective cohort studies and randomized controlled trials, the highest level of evidence."

Blueprint: The 10 Recommendations

"Our 10 recommendations form a blueprint for healthy living to reduce the risk of cancer," said Dr Brockton. "The recommendations are practical and achievable steps that everyone can take to reduce their risk of cancer, and while any small steps that people can take will help, the recommendations are intended as an overall lifestyle package."

He emphasized that "there is good evidence that the more closely people follow them, the lower their risk of developing cancer."

The first recommendation is to be a healthy weight, given the particularly strong evidence that greater body fatness is a cause of many cancers.

The second 2 recommendations are to be physically active and to consume a diet that is rich in whole grains, vegetables, fruit, and beans. These steps both the risk for cancer as well as for weight gain and being overweight or obese.

The next 4 recommendations focus on limiting consumption of certain products; namely, fast foods and other processed foods high in fat, starches, or sugars; red and processed meat; sugar-sweetened drinks; and alcohol intake.

The eighth recommendation is not to use high-dose dietary supplements for cancer prevention; instead, the goal should be to meet nutritional needs through diet alone.

The final 2 recommendations focus on specific population subgroups.

New mothers should breastfeed their babies, if possible. This recommendation aligns with that from the World Health Organization, which recommends that infants should be exclusively breastfed for 6 months, and then up to 2 years of age or beyond, alongside appropriate complementary foods.

The other subgroup are individuals who have already received a cancer diagnosis. The report notes the increased recognition of the potential importance of diet, nutrition, physical activity, and body weight in cancer survival. Individuals with a cancer diagnosis should consult an appropriately trained health professional as soon as possible who can take each person's circumstances into account. But unless advised otherwise, and if at all possible, cancer survivors are advised to follow the 8 previous recommendations after the acute stage of treatment.

Formidable Challenge of Changing Lifestyle

Now that the evidence is strong, the next formidable challenge is getting people, on a large population level, to change lifestyle factors.

"The first step in making changes is the awareness that changes need to be made," explained Dr Brockton. "The 2017 AICR Cancer Risk Awareness Survey revealed that less than 50% of respondents knew that having overweight or obesity was linked to cancer, despite it being linked to 12 types of cancer."

"This report provides the robust and reliable scientific evidence to support individuals to make effective changes to their lifestyle, health professionals to advise their patients, and governments to implement policies that make healthier choices more accessible and affordable," he said.

"We call on governments to prioritize cancer prevention through the development and implementation of effective policies in order to address the rising burden of cancer in the US," he added

Rowan Chlebowski, MD, PhD, chief, Division of Medical Oncology and Hematology; City of Hope National Medical Center, Duarte, California, agreed. "I believe that the evidence is strong enough to make a compelling case that people should take the 10 recommendations for cancer prevention seriously," he said in a statement. "A good number of scientific studies support the concept that cancer can be prevented with diet, nutrition, weight management, and physical activity."

Diet, Nutrition, Physical Activity and Cancer: a Global Perspective. World Cancer Research Fund/AICR. 2018.^[1]

Clinical Implications

• The current cancer prevention guidelines stress a healthy diet and exercise to achieve a healthy body weight. Even high-normal body mass index values may be associated with a higher risk for cancer, and the recommendations endorse the guidelines for physical activity promoted by the World Health Organization. Red meat consumption should be limited to 3 servings per week at most, and it is best to eliminate alcohol entirely to reduce the risk for cancer.
• Other recommendations to prevent cancer include breastfeeding and discouraging the use of supplements. Patients with a history of cancer should also follow the general recommendations, to the degree that they are able.
• Implications for the Healthcare Team: These recommendations demonstrate the importance of addressing health habits during the office visit, particularly diet and exercise. Patients who are overweight or obese should receive weight loss counseling and more aggressive care if they are unable to lose weight.

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