A large study of older adults in the United States shows that metabolic syndrome significantly reduces survival after breast or prostate cancer, highlighting the potential value of integrating metabolic health management into routine cancer care.
Research: Metabolic syndrome is associated with increased mortality in breast or prostate cancer patients. Image credit: TarikVision / Shutterstock
In a recent “press article” published in the journal scientific reportResearchers evaluated the association between metabolic syndrome and overall, cancer-specific, cardiovascular-specific, and liver failure-specific mortality in older patients with breast and prostate cancer.
background
Almost one in two adults over the age of 60 is affected by metabolic syndrome, making it a major public health concern alongside cancer. Metabolic syndrome is clinically defined as the co-occurrence of at least three metabolic abnormalities, including hypertension, hyperlipidemia, elevated triglyceride levels, central adiposity, and low high-density lipoprotein cholesterol levels.
These abnormalities are simultaneously associated with chronic inflammation, altered hormonal signaling, and insulin resistance, which may be associated with cancer development and progression. Breast and prostate cancers are particularly relevant because many tumors are affected by hormonal pathways that intersect with metabolic processes. However, previous studies have shown conflicting results regarding the impact of metabolic syndrome on survival. Further research is needed to clarify these associations and guide effective clinical and lifestyle interventions.
About research
Researchers conducted a retrospective observational study using the Surveillance, Epidemiology, and End Results (SEER) and Medicare linked databases, which combine population-based cancer registry information and Medicare claims data. The study included participants aged 66 and older who were newly diagnosed with primary prostate or breast cancer for the first time between 2008 and 2019.
The study excluded patients whose cancer was identified only by an autopsy report or death certificate, those with a history of cancer, those who were not continuously enrolled in Medicare Parts A, B, or D, or those who were enrolled in a health maintenance organization during the 24-month period from 12 months before diagnosis to 12 months after diagnosis. Survival analysis began 12 months after cancer diagnosis based on a prespecified landmark design, after metabolic syndrome was assessed in the first year after diagnosis.
Metabolic syndrome was identified from Medicare claims using International Classification of Diseases, Ninth Revision, Clinical Revision, International Classification of Diseases, Tenth Revision, Clinical Revision, Current Procedural Terminology/Medical Common Procedural Coding System codes, and prescription claims for medications used to treat associated metabolic diseases.
Patients were classified as having metabolic syndrome if they had claims that directly coded for metabolic syndrome or claims for at least three conditions: hypertension, hyperlipidemia, obesity, type 2 diabetes, or low high-density lipoprotein cholesterol levels. Most outpatient and prescription-based definitions required at least two claims or medication fills at least 30 days apart.
The primary outcomes were all-cause mortality, cancer-specific mortality, cardiovascular-specific mortality, and liver failure-specific mortality. Multivariate Cox proportional hazards regression models were used to estimate hazard ratios while adjusting for demographic characteristics, cancer stage, geographic region, socioeconomic status, and additional disease-specific factors such as androgen deprivation therapy in the prostate cancer model and tumor subtype in the breast cancer model.
Research results
The study included 104,599 breast cancer patients and 96,005 prostate cancer patients who met eligibility criteria. Metabolic syndrome was identified in 29,562 (28%) breast cancer patients and 29,504 (31%) prostate cancer patients.
Most participants in both groups had localized or localized disease at the time of diagnosis. Breast cancer patients were diagnosed at a median age of 74 years, and prostate cancer patients were diagnosed at a median age of 73 years. Patients with metabolic syndrome were generally older than patients without metabolic syndrome, and both cohorts had higher proportions of Hispanic and non-Hispanic black patients.
The study found that metabolic syndrome was associated with a significantly higher adjusted risk of death from any cause in both types of cancer. Among breast cancer patients, those with metabolic syndrome had approximately twice the adjusted hazard of all-cause death compared with those without metabolic syndrome (hazard ratio (HR) 2.03, 95% confidence interval (CI) 1.98-2.08).
A similar increased association was observed in patients with prostate cancer (HR 2.21; 95% CI 2.15-2.27). Kaplan-Meier analysis showed that patients with metabolic syndrome had a lower probability of overall survival during follow-up.
Findings also revealed that metabolic syndrome is associated with an increased risk of cancer-specific mortality. Patients with breast cancer and metabolic syndrome had a 30% higher adjusted hazard of death from breast cancer (HR 1.30; 95% CI 1.21-1.39). Meanwhile, patients diagnosed with prostate cancer and metabolic syndrome had a 32% higher adjusted hazard of death from prostate cancer (HR 1.32; 95% CI 1.22-1.42).
Although the data showed that metabolic syndrome was associated with both all-cause mortality and cancer-specific mortality, the observations did not establish a causal relationship. However, sensitivity analyzes limited to metabolic syndrome recorded in the 12 months before cancer diagnosis found no significant association with cancer-specific mortality in either cohort, although associations with all-cause mortality, cardiovascular-specific mortality, and liver failure-specific mortality remained high.
Metabolic syndrome was also associated with a higher risk of cardiovascular mortality in cancer patients. Patients with breast cancer and metabolic syndrome had more than double the adjusted hazard of cardiovascular-specific death compared to patients without metabolic syndrome (HR 2.27; 95% CI 2.11-2.45).
Similarly, patients with prostate cancer had a significantly higher adjusted hazard of cardiovascular-specific mortality (HR 2.46; 95% CI 2.27-2.66). Furthermore, metabolic syndrome was associated with substantially higher liver failure-specific mortality in both cohorts.
In breast cancer patients, metabolic syndrome was associated with an HR of 2.55 (95% CI 1.48-4.42), while in prostate cancer patients, the HR was 3.26 (95% CI 1.83-5.82). Relatively wide confidence intervals indicate low precision of these liver failure estimates.
Overall, this study showed that metabolic syndrome was associated with decreased survival and increased cause-specific mortality in older cancer patients after adjusting for measured covariates.
conclusion
In the primary analysis, metabolic syndrome was associated with increased overall, cancer-specific, cardiovascular-specific, and liver failure-specific mortality in older patients with breast and prostate cancer. Although these findings identify metabolic syndrome as a marker of poor long-term outcome after cancer diagnosis, they do not establish that metabolic syndrome is the cause of metabolic syndrome.
This study supports evaluating whether integrating cardiometabolic management and routine cancer treatment, alongside lifestyle interventions and appropriate treatment strategies, can help reduce mortality in this population.
Interpretation is limited by the retrospective design, claims-based classification of metabolic syndrome, uncertain timing of exposure, and potential for residual confounding. Additionally, the findings may not apply to younger patients, those enrolled in Medicare Advantage, or those with commercial insurance.
Further research is needed to understand how metabolic syndrome affects cancer outcomes and to identify effective interventions that improve survival while addressing metabolic health.
Reference magazines:
- Huang, J.P., Chan, N., Missoy, M.W., Gal, S., Lazuki, Z.A., Gregg, J.R., Heredia, N.I., and Giordano, S.H. (2026). Metabolic syndrome is associated with increased mortality in breast or prostate cancer patients. scientific report. Doi: doi: 10.1038/s41598-026-58830-2, https://www.nature.com/articles/s41598-026-58830-2
