Breast Cancer's Dual Threat: Obesity and Metabolic Syndrome

A recent study has highlighted the distinct associations between metabolic syndrome, obesity, and breast cancer. Published in the journal Cancer, the research revealed that a higher metabolic syndrome score correlates with increased breast cancer mortality, while obesity is linked to a higher incidence of the disease.

The study examined data from 63,330 women who had no prior history of breast cancer and who received annual mammograms as part of the Women’s Health Initiative. The follow-up period spanned approximately 20 years, during which researchers tracked breast cancer incidence, mortality, deaths post-diagnosis, and hormone receptor status.

Over the study period, there were 4,562 breast cancer cases and 2,073 deaths following a diagnosis, with 659 of these deaths directly attributed to breast cancer. At the outset, data on body mass index (BMI) and metabolic scores (ranging from 0 to 4, based on waist circumference, blood sugar levels, blood pressure, and cholesterol) were collected.

The researchers found that both metabolic syndrome and obesity significantly influenced breast cancer outcomes, but in different ways. Adjusting for BMI, they noted that a higher metabolic score (3-4) was linked to more aggressive estrogen receptor (ER)-positive and progesterone receptor (PR)-negative breast cancers. This higher score was also associated with a 53% increase in deaths following a breast cancer diagnosis and a 44% higher overall breast cancer mortality.

Conversely, when adjusting for metabolic score, obesity was found to be related to a greater overall incidence of breast cancer, particularly those with a favorable prognosis (ER-positive, PR-positive). Obesity also contributed to an increase in deaths post-diagnosis, with severe obesity correlating with higher breast cancer mortality.

The study also suggested that a low-fat diet might help reduce breast cancer mortality, particularly among women with components of metabolic syndrome, such as obesity, high blood pressure, elevated blood sugar, and abnormal cholesterol levels.

Dr. Parvin Peddi, a medical oncologist and director of Breast Medical Oncology at the Margie Petersen Breast Center at Providence Saint John’s Health Center, emphasized that both obesity and conditions like hypertension, diabetes, and high cholesterol can increase breast cancer incidence. She noted that a composite metabolic syndrome score, reflecting the presence of these conditions, was associated with more severe breast cancers (ER-positive and PR-negative).