Effect of metabolic syndrome on survival among patients with breast or prostate cancer.

e22615 Background: Metabolic syndrome is defined as the presence of at least 3 of the following metabolic conditions: dysglycemia, hypertension, elevated triglyceride levels, low high-density lipoprotein levels, and central adiposity. Patients with cancer and metabolic syndrome have increased risk of adverse clinical outcomes. Metabolic syndrome may be particularly of interest in patients with hormonally driven cancers, in whom hormonal and environmental risk factors for cancer overlap with risk factors for metabolic syndrome. We investigated the long-term association of metabolic syndrome with overall survival, cancer-specific mortality, and non-cancer-specific mortality in patients with breast or prostate cancer using real-world data. Methods: Using SEER-Medicare linked data, we selected breast cancer patients and prostate cancer patients who were diagnosed during 2008-2019, had no previous cancer diagnosis, and were aged 66 years or older at diagnosis. From these patients, we excluded those not continuously insured with Medicare Parts A, B, and D from 12 months before through 12 months after cancer diagnosis or patients with cancer diagnosis based on autopsy or death certificate only. Patients with metabolic syndrome were identified using ICD-9-CM and ICD-10-CM codes, CPT/HCPCS codes, and prescription drug use. A multivariate Cox regression model using metabolic syndrome as the exposure variable and adjusted for age at diagnosis, race/ethnicity, marital status, year of diagnosis, cancer stage, SEER region, and metropolitan area was applied for overall survival, cancer-specific mortality, and non-cancer-specific mortality analysis. Results: A total of 104,599 breast cancer patients and 96,005 prostate cancer patients met the selection criteria. The prevalence of metabolic syndrome was 28% among breast cancer patients and 31% among prostate cancer patients. Metabolic syndrome was associated with higher risk of death overall among both breast cancer patients (HR 1.62; 95% CI: 1.58, 1.66) and prostate cancer patients (HR 1.83; 95% CI: 1.78, 1.88). Metabolic syndrome was associated with slightly lower risk of cancer-specific death among breast cancer patients (HR 0.94; 95% CI: 0.88, 0.99) and slightly higher risk of cancer-specific death among prostate cancer patients (HR 1.08, 95% CI 1.01-1.15). In both cohorts, metabolic syndrome was associated with higher risk of death from cardiovascular disease (breast cancer HR 1.94, 95% CI: 1.81, 2.08; prostate cancer HR 2.12, 95% CI: 1.97, 2.27) or liver failure (breast cancer HR 2.36; 95% CI: 1.44, 3.85; prostate cancer HR 2.66; 95% CI: 1.58, 4.49). Conclusions: Among patients with breast or prostate cancer, metabolic syndrome is associated with increased risk of dying from all causes, cardiovascular disease, or liver failure. Future therapeutic and lifestyle interventions are needed to reduce the risk of mortality in these patients.