Poor Diet Implicated in Premenopausal Breast Cancer

Karin B, Michels, ScD, PhD

Karin B, Michels, ScD, PhD

Poor diet in adolescence and early adulthood may increase a woman’s risk of developing breast cancer before menopause, according to a study recently published in the journal Cancer Epidemiology, Biomarkers & Prevention.

Researchers from the UCLA Fielding School of Public Health examined the potential effect of a diet associated with chronic inflammation on breast cancer. This kind of a diet consists of little vegetable consumption and is high in sugar-sweetened drinks, diet soft drinks, refined sugars and carbohydrates, red and processed meats, as well as margarine. These foods have all been linked to high levels of inflammatory markers in the blood, explained Karin B. Michels, ScD, PhD, professor and chair of the Department of Epidemiology.

“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,” Michels said.

She and her colleagues used data from 45,204 women enrolled in the Nurses’ Health Study II, which began in 1989 to study oral contraceptives, diet and lifestyle risk factors among young nurses aged 25-42 years.

That study first examined adult diet in 1991 using a food frequency questionnaire, when the women were between 27 and 44 years old. In 1998, when the women were aged 33 to 52, they completed another food frequency questionnaire about their diet during high school. The questionnaires continue to be administered at 4-year intervals.

Researchers in this most recent study concluded that 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.

Each woman’s diet was given an inflammatory score, using a method that links diet with inflammatory markers in the blood, and the women were then divided into 5 groups based on their score. Those women in the highest score group for adolescent diet had a 35% higher risk for premenopausal breast cancer relative to those in the lowest score group.

The same analysis was conducted based on early adulthood diet, and researchers determined that those in the highest inflammatory score group had a 41% 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.

“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,” she said.

The authors noted 2 main limitations to the study. First, patients were asked to remember diet during adolescence at a later date. The researchers also did not have adolescent or early adulthood measurements of blood markers of inflammation in this study.

“About 12% of women in the United States develop breast cancer in their lifetimes,” said Michels. “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.”

Harris HR, Willett WC, Vaidya RL, Michels KB. An adolescent and early adulthood dietary pattern associated with inflammation and the incidence of breast cancer. Cancer Res. 2017;77(5):1179-1187.