Abstract P1-15-03: Assessing the association of statins with clinical outcomes in women with breast cancer
Authors: Chongxi Ren , Jianna Sun , Lingjun Kong 
Published: March 2022

Abstract
Background: A growing number of studies are claiming lipid-lowering medications (LLMs) primarily statins have anticancer properties to inhibit proliferation, activate apoptosis, and reduce metastasis, but the clinical evidence applied to breast cancer remains inconsistent. Aim: To review and evaluate the association between statin use and clinical outcome in women with breast cancer. Settings and design: A systematic review and meta-analysis of the literature were carried out. It was designed and performed in accordance with the MOOSE and Cochrane’s Handbook guidelines. Methods: We conducted a systematic review and meta-analysis of observational studies published from database inception to Feb 28, 2021, which reported the effect of statin use on prognosis in women with breast cancer. Studies were identified by searches in PubMed, MEDLINE, Embase, the Cochrane Central Register of Controlled Trials, and by hand searching of previous publications. The review and meta-analysis were conducted to assess the effect of statin use on clinical outcomes in women with breast cancer. The associations between statin use and breast cancer recurrence and mortality were measured by hazard ratios (HRs) in this study. Robustness of pooled estimates from random-effects models was considered with sensitivity analyses, meta-regression, and subgroup analyses. All statistical analyses were performed with Stata 16.0. Findings: Twenty-two cohort studies (9 prospective and 13 retrospective) with 210,711 women with breast cancer were included. Statin use was defined as statin exposure before, at, and after the diagnosis of breast cancer in different studies. The follow-up durations varied from 1 to 7 years. Pooled results with a random-effect model showed that statin use was significantly associated with a lower risk of breast cancer recurrence (adjusted HR=0.72, 95% CI: 0.62 to 0.85, p&lt;0.01, I2=23.06%); and the pooled results showed that statin use was associated with a significantly reduced risk of breast cancer mortality (adjusted HR=0.79, 95% CI: 0.72 to 0.88; p&lt; 0.01) with significant heterogeneity (I2=79.29%). Subgroup analysis showed that study design, sample size, statin type, timing of statin use, or quality score did not significantly affect the outcomes. Interpretation: Due to the paucity of randomized controlled trials exploring statin use in patients with breast cancer, this was a meta-analysis which included retrospective and prospective cohort studies. Admittedly, there was substantial heterogeneity across the studies both in the main and subgroup analysis of breast cancer, and, although we combined HR data after multivariate adjustment, residual factors that potentially confound the association between statin use and prognosis in breast cancer may remain existing. Next, definition and exposure time of statin use among the included studies varied, and our results of subgroup analyses were based on data of study level rather than individual patient level. In addition, the causality regarding statin use and improved prognosis in women with breast cancer should not be retrieved from our results. However, it is the most comprehensive meta-analysis on the use of statins and clinical outcomes in women with breast cancer to date. Given the limited toxicity profile, low cost, and ease of use of statins, identifying an association between statin therapy and improved breast cancer outcomes may have important public health implications. Conclusions: Statin use was associated with a risk-reduction of recurrence and mortality among women with breast cancer. Our data suggest that statins may have a role as an adjuvant therapy in select patients with breast cancer and supports further investigation accessed through randomized controlled trials. Key words: Breast cancer; Statin; Recurrence; Mortality; Meta-analysis
Citation Format: Ren Chongxi, Sun Jianna, Kong Lingjun. Assessing the association of statins with clinical outcomes in women with breast cancer [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P1-15-03.