The importance of regulating and improving the tumor immune microenvironment is increasingly being recognized. While it has been reported that therapeutic agents for hyperlipidemia, in particular statins, can induce cancer cell growth suppression and anti-metastatic effects in breast cancer, few studies have investigated the correlation between improvement of lipid metabolism and antitumor immune response and cancer prognosis in vivo.
Except for patients with ductal carcinoma in situ, 938 breast cancer patients treated with curative surgery were examined. The correlation between serum levels of total-cholesterol and triglyceride, and clinicopathological features, including pre- and postoperative neutrophil-to-lymphocyte ratio (NLR) and tumor-infiltrating lymphocytes (TILs), and prognosis was evaluated retrospectively.
194 patients were receiving treatment for hyperlipidemia. Recurrence-free survival (RFS) and overall survival (OS) did not differ significantly between users of the drug for hyperlipidemia or non-users (p = 0.782, log-rank) (p = 0.304, log-rank). Among postmenopausal patients with hormone receptor (HR)-positive/human epidermal growth factor receptor 2 (HER2)-negative breast cancer, who were treated for hyperlipidemia, the group with good serum lipid control had significantly better RFS (p = 0.014, log-rank). Good serum lipid control was also significantly correlated with low postoperative NLR (p = 0.024). In addition, high-TILs in resected tissues was significantly associated with preoperative serum lipid levels (p = 0.039). In the drug type, lipophilic statin users had lower recurrence rate than hydrophilic statin users (8.2 % vs 16.0 %).
Good control of serum lipid metabolism may have a relationship with improvement of tumor immune microenvironment and favorable outcome in postmenopausal HR-positive/HER2-negative breast cancer patients.
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