In a group of 176 breast cancer patients, significantly more women with metabolic syndrome than without it had triple negative breast cancer. Triple negative refers to tumors that are estrogen receptor negative (ER-), progesterone receptor negative (ER-), and HER2/neu negative. In other words, triple negative breast cancers do not express receptors for estrogen or progesterone and do not overexpress HER2. Triple negative breast cancer tends to be more aggressive and with a poorer outcome than hormone receptor positive breast cancer.

Metabolic syndrome

Metabolic syndrome is a state of insulin resistance characterized by high waist-to-hip ratio, high body mass index (BMI), high triglyceride level, low high-density lipoprotein (HDL) cholesterol, above normal fasting glucose, high blood pressure and polycystic ovarian syndrome. Not all of these factors have to be present for a diagnosis of metabolic syndrome. In the study, elevated triglyceride, HDL cholesterol, and glucose levels (but not high blood pressure or high body mass index) each were found to be independently associated with triple negative breast cancer.

Implications for breast cancer survival

For women who already have been diagnosed with triple negative breast cancer, this study underscores the importance of reducing cholesterol and getting blood sugar under control if either are outside desirable ranges. This conclusion is based on the theory that factors found to be associated with breast cancer diagnosis also tend to promote breast cancer recurrence. The study suggests that there would be a benefit to taking these steps even in the absence of weight loss.

Women with a BRCA1 breast cancer gene mutation are more likely to develop ER-/PR- breast cancer than hormone receptor-positive breast cancer. The new study suggests that reducing cholesterol and getting blood sugar under control, if indicated, are also very important for BRCA1 carriers.