breast cancer

Researchers in the U.S. investigate the relationship between exercise and weight loss and tumor recurrence in breast cancer survivors.

Over 200,000 women are diagnosed with breast cancer in the U.S. each year. Only 10% of these cases are due to a genetic predisposition for breast cancer, which suggests that environmental and lifestyle factors are at play. Alcohol intake, smoking, and poor diet are among the lifestyle factors associated with a higher risk of breast cancer-related death.

In post-menopausal women, studies show that obesity also increases the risk of breast cancer-related death compared to women with a normal body mass index (BMI). Among breast cancer survivors, weight gain is associated with a 64% increased risk of breast cancer death. In fact, obesity rates are increasing faster in post-menopausal women with a history of cancer compared to women without a history of cancer. Therefore, scientists are working to better understand the molecular factors associated with obesity-related breast cancer recurrence.

A team of American researchers studied body mass index and its relationship to cancer-related microRNAs (miRNAs). MicroRNAs are involved in regulating processes inside cells and are very dysregulated in patients with cancer.

A recent study published in Breast Cancer Research and Treatment looked for correlations between body mass index and microRNA expression in the blood serum of 121 inactive, post-menopausal breast cancer survivors. Blood serum samples from two previous breast cancer clinical trials were examined to assess the effect of a weight loss intervention on microRNA expression over six months. In the first study, the weight loss interventions included 150 minutes of aerobic exercise per week and twice-weekly strength training. In the second study, the participants received either in-person or telephone weight loss counseling.

After analyzing the serum samples from each study, eight microRNAs were found to be significantly associated with body mass index. Additionally, the expression levels of six microRNAs were significantly different in patients who received weight loss counseling compared to those who did not.

Future research will focus on studying these specific microRNAs to discover their roles in the molecular pathways associated with breast cancer. Ultimately, this work may help explain the link between body mass index and increased breast cancer risk.

Written by Cindi A. Hoover, Ph.D.

Reference: Adams BD, Arem H, Hubal MJ et al. Exercise and weight loss interventions and miRNA expression in women with breast cancer. Breast Cancer Res Treat. 2018. (https://doi.org/10.1007/s10549-018-4738-6

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