Association of serum lipid levels and clinical outcomes in early breast cancer patients

BACKGROUND: The association between dyslipidaemia and breast cancer remains controversial, especially regarding the dynamic changes in lipid levels. OBJECTIVES: This study aimed to elucidate the role of serum lipid levels and the changes in disease outcomes in patients with breast cancer. METHODS: The lipid profiles of patients with breast cancer who underwent surgery between 2013 and 2017 were retrospectively reviewed. The lipid profiles comprised triglyceride (TG), total cholesterol, high-density lipoprotein (HDL), and low-density lipoprotein. Serum lipid levels were categorized into three groups based on the tertiles. The Wilcoxon test was used to compare changes in serum lipid levels during follow-up. Hazard ratios (HRs) for survival outcomes were estimated using a multivariate Cox regression analysis. RESULTS: A total of 3499 women diagnosed with nonmetastatic invasive breast cancer were included in this study, with a median follow-up of 60.4 months. We confirmed that each 1-tertile increased TG at baseline [HR = 1.19, 95% confidence interval (CI) 1.02–1.39] and 1-year follow-up (HR = 1.46, 95% CI 1.07–1.98) led to worse relapse-free survival (RFS). A lower risk of disease relapse was observed with each 1-tertile upregulation in HDL at 1-year follow-up (HR = 0.72, 95% CI 0.56–0.92). Receiving systemic therapies tends to induce an elevation in plasma lipid levels 1 year after surgery, especially in terms of TG. Regarding the prognostic value of dynamic changes in lipid levels, patients with sustained high levels of TG had poorer RFS (HR = 1.90, 95% CI 1.16–3.11), whereas maintaining high levels of HDL led to better survival (HR = 0.60, 95% CI 0.37–0.97). CONCLUSION: High TG at baseline and during follow-up was associated with worse disease outcome in early breast cancer patients. Systemic treatment would lead to an elevation of serum lipid levels. Patients with sustained high HDL level at 1-year follow-up after surgery had a superior prognosis, warranting further clinical evaluation.