Bottom Line: Women who consumed a diet as adolescents or young adults associated with chronic inflammation had a higher risk for premenopausal breast cancer compared with those whose adolescent and early adulthood diet was not associated with chronic inflammation
Journal in Which the Study was Published: Cancer Epidemiology, Biomarkers & Prevention, a journal of the American Association for Cancer Research.
Author: Karin B. Michels, ScD, PhD, professor and chair of the Department of Epidemiology at the UCLA Fielding School of Public Health, Los Angeles.
Background: A diet low in vegetables and high in sugar-sweetened and diet soft drinks, refined sugars and carbohydrates, red and processed meats, and margarine has been linked to high levels of inflammatory markers in the blood, according to Michels.
"Because breast cancer takes many years to arise, we were curious whether such a diet during the early phases of a woman's life is a risk factor for breast cancer," she said.
How the Study Was Conducted and Results: For this study, Michels and colleagues used data from 45,204 women enrolled in the Nurses' Health Study II who had completed a food frequency questionnaire in 1998, when they were ages 33-52, about their diet during high school. Adult diet was assessed first using a food frequency questionnaire in 1991, when participants were ages 27-44, and then every four years after that. Each woman's diet was given an inflammatory score using a method previously developed that links diet with inflammatory markers in the blood.
During 22 years of follow-up, 870 of the women who completed the high school food frequency questionnaire were diagnosed with premenopausal breast cancer and 490 were diagnosed with postmenopausal breast cancer.
When women were divided into five groups based on the inflammatory score of their adolescent diet, those in the highest score group had a 35 percent higher risk for premenopausal breast cancer relative to those in the lowest score group. When the same analysis was done based on early adulthood diet, those in the highest inflammatory score group had a 41 percent higher risk for premenopausal breast cancer relative to those in the lowest score group.
Diet inflammatory score was not associated with overall breast cancer incidence or postmenopausal breast cancer.
Author Comment: "Our results suggest that a habitual diet that promotes chronic inflammation when consumed during adolescence or early adulthood may indeed increase the risk of breast cancer in younger women before menopause," said Michels.
"About 12 percent of women in the United States develop breast cancer in their lifetimes," she added. "However, each woman's breast cancer risk is different based on numerous factors, including genetic predisposition, demographics, and lifestyle. Our study suggests that a habitual adolescent/early adulthood diet that promotes chronic inflammation may be another factor that impacts an individual woman's risk.
"During adolescence and early adulthood, when the mammary gland is rapidly developing and is therefore particularly susceptible to lifestyle factors, it is important to consume a diet rich in vegetables, fruit, whole grains, nuts, seeds, and legumes and to avoid soda consumption and a high intake of sugar, refined carbohydrates, and red and processed meats," Michels noted.
Limitations: According to Michels, it is important to note that although this is an association study, it is not feasible to perform a causal study because that would require randomizing individuals to a particular diet for a long period of time and following them for decades. She also explained that the main limitations of the current study are that diet during adolescence was recalled by the participants at a later date and that the researchers did not have adolescent or early adulthood measurements of blood markers of inflammation in this study.
Funding & Disclosures: Grants from the National Cancer Institute supported this study and continue to support the Nurses' Health Study II. Michels declares no conflicts of interest.
About the American Association for Cancer Research
Founded in 1907, the American Association for Cancer Research (AACR) is the world's first and largest professional organization dedicated to advancing cancer research and its mission to prevent and cure cancer. AACR membership includes more than 37,000 laboratory, translational, and clinical researchers; population scientists; other health care professionals; and patient advocates residing in 108 countries. The AACR marshals the full spectrum of expertise of the cancer community to accelerate progress in the prevention, biology, diagnosis, and treatment of cancer by annually convening more than 30 conferences and educational workshops, the largest of which is the AACR Annual Meeting with nearly 19,500 attendees. In addition, the AACR publishes eight prestigious, peer-reviewed scientific journals and a magazine for cancer survivors, patients, and their caregivers. The AACR funds meritorious research directly as well as in cooperation with numerous cancer organizations. As the Scientific Partner of Stand Up To Cancer, the AACR provides expert peer review, grants administration, and scientific oversight of team science and individual investigator grants in cancer research that have the potential for near-term patient benefit. The AACR actively communicates with legislators and other policymakers about the value of cancer research and related biomedical science in saving lives from cancer. For more information about the AACR, visit http://www.
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