Breast cancer survivors with metabolic syndrome may have an elevated likelihood of breast cancer recurrence and subsequent breast cancer–related mortality, according to new findings to be presented by Harborg et al at the European Congress on Obesity (ECO) 2025, taking place between May 11 and 14 in Spain, and published in the Journal of Internal Medicine.
Study Methods and Results
In the study, investigators obtained survival data from observational studies and randomized controlled trials involving 42,135 breast cancer survivors to examine how the incidence of metabolic syndrome at the time of breast cancer diagnosis may be associated with survival outcomes. They performed statistical modelling to pool the study data and assess the relationship between an unhealthy metabolic profile and breast cancer survival.
The investigators used criteria from the American Heart Association to characterize metabolic syndrome as the presence of three out of five abnormal findings among the risk factors: high blood pressure, high triglycerides, low high-density lipoprotein (HDL) cholesterol, high fasting glucose, and central or abdominal obesity (a waist circumference of over 35 inches among women).
The pooled estimates revealed that breast cancer survivors who had metabolic syndrome at the time of their breast cancer diagnosis experienced a 69% increased risk of breast cancer recurrence and an 83% increased risk of breast cancer–related mortality compared with breast cancer survivors without metabolic syndrome. Additionally, the breast cancer survivors with metabolic syndrome were 57% more likely to experience a breast cancer–related adverse event—including breast cancer recurrence, the occurrence of a new cancer, or mortality—during the follow-up period compared with breast cancer survivors without metabolic syndrome.
The investigators explored the potential differences in the association between metabolic syndrome and adverse events according to geographical location of the included studies. Notably, they discovered that the correlation between poorer outcomes among breast cancer survivors with metabolic syndrome was consistent across Europe, North America, and Asia.
Conclusions
“Among breast cancer survivors, metabolic syndrome was associated with poorer breast cancer outcomes. The findings of this study emphasize the importance of metabolic screening for breast cancer survivors,” the study authors indicated. “Future research should focus on assessing how control of blood fats, reversing diabetes, and making healthy lifestyle choices could decrease the prevalence of metabolic syndrome in this population and ultimately enhance breast cancer survival,” they added.
The investigators that although the precise mechanisms through which metabolic syndrome heightened the risk of breast cancer and its recurrence remain unclear, they believe the association could involve chronic inflammation and hormonal imbalances.
“One possible explanation posits that the excessive body fat associated with metabolic syndrome results in increased levels of circulating estrogen, which may stimulate the growth of breast cancer cells. Additionally, adiposity may induce alterations in the tumor microenvironment that facilitate metastasis, or the spread of cancer. Chronic systemic inflammation, a hallmark of metabolic syndrome, may further contribute to tumor progression by promoting cancer cell survival and impairing immune surveillance,” the study authors underscored. “Although our study did not investigate the biological underpinnings of the observed associations, it is likely that multiple interacting mechanisms—primarily driven by obesity-induced molecular changes and chronic inflammation—underlie the link between metabolic syndrome and poor breast cancer outcomes,” they concluded.
Disclosure: For full disclosure of study authors, visit the Journal of Internal Medicine.
