Research points to chronic inflammation playing a key role in heightening the risk of many cancers, along with heart disease. A study suggests that postmenopausal breast cancer survivors who consume an anti-inflammatory diet after diagnosis, filled with whole grains, fish, and vegetables, have a lower risk of dying from cardiovascular disease compared to survivors eating a pro-inflammatory diet. The study, published last month in Cancer Epidemiology Biomarkers & Prevention, was partially supported by AICR.
The findings come at a time when efforts are being made to raise awareness that breast cancer survivors face a heightened risk for heart disease. Earlier this month, the American Heart Association issued a scientific statement highlighting that breast cancer survivors, especially older women, are more likely to die from cardiovascular diseases such as heart failure rather than breast cancer. Some breast cancer therapies can damage the heart, underscoring the importance of effectively managing heart disease risk factors during and following cancer treatment, their research concluded. “We know that cardiovascular disease is a leading cause of death among breast cancer survivors, and there was reason to believe from previous studies that diet quality may be important, but no one had looked at inflammatory diet potential,” said principal investigator of the study and AICR grantee Susan E. Steck, PhD, MPH, RD, Associate Professor at University of South Carolina (USC).
Breast Cancer Survivorship
For the study, Steck and her colleagues used a dietary index that they had developed based on how 45 foods and food components affect six compounds linked to inflammation. The index rates the potential of how these foods and compounds will affect inflammation in a person. Fiber, certain spices, and nutrients found in many vegetables and fruits rank as having a high potential to lower inflammation, while saturated fat, trans fat and cholesterol have pro-inflammatory scores on the index.
Approximately 1.5 years after diagnosis, 2,150 postmenopausal women filled out questionnaires about what they typically ate and other lifestyle factors. The women were part of the national Women’s Health Initiative study where data on supplement use was also collected. Inflammatory index scores were calculated from both food and supplement use.
After an average of about 13 years, the breast cancer survivors categorized as having the most anti-inflammatory diets had a 56 percent lower risk of dying from cardiovascular disease, compared with women who consumed the most pro-inflammatory diets. This was after researchers adjusted for key risk factors, including age, physical activity and BMI.
There was no link to an anti-inflammatory diet with mortality from breast cancer specifically. There was also no link to dying from all causes combined.
“It’s possible that inflammation may not play as strong a role for breast cancer specifically as it does for other cancers, like colorectal or pancreatic, though it is still important in multiple chronic diseases,” says Steck.
The study has several limitations, including that the women only reported their dietary habits once, and that may have changed over time. And some of the dietary components in the USC inflammatory index was missing from the questionnaires.
The next step is a larger study and to investigate if the USC dietary inflammatory index links to survival for women diagnosed with certain hormone-specific breast tumors. What the scientists have found, from this and other anti-inflammatory diet studies, is that benefits appear to come from not one food or food component, but a pattern of eating.
“Chronic inflammation is central to both cardiovascular disease and cancer,” says Nigel Brockton, PhD, AICR's Director of Research. “The current study demonstrates that diets associated with higher inflammation are linked to higher risk of death from cardiovascular disease in breast cancer survivors. Understanding how diet impacts chronic inflammation and related health outcomes, could provide strategies to monitor and reduce it through diet and lifestyle recommendations.”
Lifestyle Matters for Breast Cancer Survivors
This study joins a growing body of research pointing to how diet and physical activity may offer health benefits to the approximately 3 million US breast cancer survivors. AICR's most recent report on breast cancer survivorship in 2014 indicated that eating more fiber-filled foods and soy, and less saturated fat may improve survival. The evidence was not strong enough to make any firm conclusions yet it supports AICR’s recommendations that eating a plant-based diet – along with keeping to a healthy weight and getting regular physical activity – remain the best strategies for all cancer survivors to follow.
"Cancer survivors don't need to wait for conclusive research on the anti-inflammatory diet," says Alice Bender, MS, RDN, Director of Nutrition Programs, "Independent studies are finding benefits for cancer survivors who follow AICR recommendations, including eating a plant-rich diet and avoiding highly processed foods."
Along with the American Institute for Cancer Research, the breast cancer survivorship study was funded by the National Cancer Institute and the National Institute of Diabetes and Digestive and Kidney Diseases.
James R Hebert, one of the study authors, owns controlling interest in a company planning to license the right to the USC in order to develop products related to the dietary inflammatory index.
Source: Jiali Zheng, Fred K. Tabung, Jiajia Zhang, Angela D. Liese, Nitin Shivappa, Judith K. Ockene, Bette Caan, Candyce H. Kroenke, James R. Hebert and Susan E Steck; Association between post-cancer diagnosis dietary inflammatory potential and mortality among invasive breast cancer survivors in the Women's Health Initiative; Cancer Epidemiol Biomarkers; January 22 2018 DOI: 10.1158/1055-9965.EPI-17-0569
Published on February 24, 2018