Poor diet in adolescence, early adulthood increases risk for premenopausal breast cancer
Women who consumed an inflammation-promoting diet during adolescence and young adulthood demonstrated increased risk for premenopausal breast cancer, according to study results published in Cancer Research.
“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,” Karin B. Michels, ScD, PhD, professor and chair of the department of epidemiology at UCLA Fielding School of Public Health, said in a press release. “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.”
Michels and colleagues used data from 45,204 women in the Nurses’ Health Study II to evaluate the association between early inflammatory diet pattern and breast cancer risk. All women completed food frequency questionnaires about the types of foods they consumed during their high school years.
After 22 years of follow-up, 870 women developed premenopausal breast cancer and 490 developed postmenopausal breast cancer.
Researchers categorized women into five groups based on the inflammatory score of their adolescent diet. Results showed women in the highest inflammatory score group had a 35% increased risk for premenopausal breast cancer compared with those in the lowest inflammatory score group.
HemOnc Today spoke with Michels about the study findings, whether an early dietary pattern could affect risk for other cancer types, and what additional research is necessary.
Question: What prompted your study?
Answer: Many studies looked at diet and breast cancer, but most did not find an association. However, we now understand that breast cancer has early origins in life. Therefore, what a woman consumes in her 70s may not be as important in terms of cancer risk as what she consumes during earlier parts of life. This is why we looked at diet earlier in a woman’s life. The other issue is that we better appreciate looking at dietary patterns. We do not consume one food in isolation; we consume many different types of foods every day. We came up with an inflammatory dietary pattern because it is more recognized that many cancers, heart disease and diabetes have inflammatory components. It seems a diet that promotes inflammation is a good one to assess.
Q: What did previous research suggest about the connection between diet and breast cancer risk?
A: There was a lack of an association between adult diet and breast cancer, with the exception of premenopausal breast cancer that is ER negative. This subgroup of breast cancers seems to be associated with a less healthy diet. In the past, researchers primarily assessed two main food patterns — a Western diet and a prudent diet. There is an association between a Western diet and ER–negative premenopausal breast cancer. However, few studies considered early life diet, and few had looked at the inflammatory dietary pattern. These are novel aspects of our study.
Q: How did you conduct the study?
A: We used data from the Nurses’ Health Study II, a cohort of 116,000 women. We included women who reported their high school diet via questionnaire. This prospective study has been ongoing for many years. Participants were asked to recall what they ate during adolescence, and we prospectively followed them over time to see who developed breast cancer and who did not. From the diet reported, we built dietary patterns and clustered foods together that were inflammation promoting. These include sugar-sweetened beverages and soft drinks, refined grains, red and processed meats, and margarine. Conversely, there is very little vegetable intake.
Q: What did you find?
A: We found that an inflammatory diet — specifically at a younger age — may indeed be important. An inflammatory diet did promote breast cancer risk — particularly premenopausal breast cancer risk — later in life.
Q: What are the clinical implications of the findings?
A: Physicians should be more aware that breast cancer is not a disease that only originates in older age. Risk factors are spread throughout a woman’s life. Moreover, parents should be counseled to teach their children to eat healthy. This is important not only in the context of heart disease and other diseases, but also in the context of cancer. Young girls may not be worried about breast cancer because it often occurs later in life, but they need to be aware that it actually develops over many decades. We need education for our children at a young age, and we need parents to be role models and explain the association between a healthy diet and the potential health risks associated with an inflammatory diet.
Q: Could diet in adolescence or early adulthood diet affect risk for other cancer types?
A: Absolutely. This is understudied, but we may learn about the risk for other cancer types in the coming years. My colleagues and I examined breast cancer because it is the most common cancer in women. Other researchers are focusing on different cancers, so I would not be surprised if we hear in the near future about associations between early life factors and other cancers.
Q: Do you plan to conduct additional research on this topic?
A: My research focuses on the puberty window of cancer susceptibility, so we are looking at a variety of factors that girls are exposed to during puberty. We are going to take a more detailed look at diet in a cohort of girls going through puberty. We will look into environmental chemicals and the role they play in breast cancer later in life. We also plan to look at the microbiome, because it is a translator or mechanism for how some of these factors may influence disease risk. We are trying to extend this research into other cohorts while asking more mechanistic questions.
Q: Is there anything else that you would like to mention?
A: Living healthy across the life course matters for maintaining health, and for the prevention of many chronic diseases. – by Jennifer Southall
Harris HR, et al. Cancer Res. 2017;doi:10.1158/00085472.CAN162273.
For more information:
Karin B. Michels, ScD, PhD, can be reached at UCLA Fielding School of Public Health, 650 Charles E. Young Drive South, Los Angeles, CA 90095; email: firstname.lastname@example.org.
Disclosure: Michels reports no relevant financial disclosures.