Impact of protein–energy malnutrition on outcomes of metastatic triple-negative breast cancer patients receiving chemotherapy: A real-world analysis.

1135 Background: Protein–energy malnutrition (PEM) is common in patients with advanced cancer and is associated with increased toxicity, decreased treatment tolerance, and worse survival across malignancies. Data specific to metastatic triple-negative breast cancer (mTNBC), a biologically aggressive subtype, remain scarce. We evaluated the impact of PEM on outcomes in mTNBC patients receiving chemotherapy. Methods: We conducted a retrospective cohort study using de-identified data from TriNetX, a global federated health research network. Females with mTNBC on chemotherapy (paclitaxel, doxorubicin, capecitabine, eribulin, vinolrebine) were identified. PEM was defined using ICD-10 codes along with secondary definitions like BMI (<20). The primary endpoint was overall survival (OS), estimated using the Kaplan-Meier method. Propensity matching was used to adjust for age, race and comorbidities. Two sided p≤0.05 was used to determine statistical significance. Results: A total of 1,644 patients with mTNBC were identified, of whom 761(46.3%) patients had PEM. The mean age was higher in the PEM group compared to the non-PEM group (64.5 vs 63 years, p <0.05). African American patients were more likely to have PEM (37.0% vs 31.4%, p =0.02). After propensity score matching, 595 patients were included in each cohort for analysis. Patients with PEM had significantly worse 1-year OS compared to non-PEM group (65.7% vs 70.8%; HR 0.76, 95% CI 0.62–0.94, p <0.05). At 2 years, survival remained numerically lower in the PEM group (56.2% vs 57.8%; HR 0.92, 95% CI 0.76–1.12), but the difference was not statistically significant. Conclusions: In this large real-world cohort of mTNBC, PEM was independently associated with worse 1-year overall survival. These findings underscore the prognostic significance of nutritional status in mTNBC and support routine nutritional assessment and early supportive interventions to improve outcomes in this high-risk population. Overall survival (OS) outcomes in matched mTNBC cohorts. Overall Survival PEM Group (n=595) Non-PEM Group (n=595) Hazard Ratio (95% CI) P-value 1-Year OS 65.7% 70.8% 0.76 (0.62–0.94) <0.05 2-Year OS 56.2% 57.8% 0.92 (0.76–1.12) 0.41