Abstract P1-15-01: Effect of concomitant statin treatment in postmenopausal patients with hormone-receptor positive early-stage breast cancer receiving adjuvant denosumab or placebo: A post-hoc analysis of ABCSG-18

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Abstract Background Statins are a common class of cholesterol-lowering drugs prescribed for the prevention and treatment of cardiovascular disease. Moreover, it was suggested that statins may possess anti-cancer properties and interact with RANK ligand expression. Therefore, we aimed at evaluating a hypothetical synergistic effect of statins with denosumab in early-stage breast cancer (BC) patients from the Austrian Breast and Colorectal Cancer Study Group (ABCSG) trial 18. Methods ABCSG-18 (NCT00556374) is a prospective, randomized, double-blind, phase III study; postmenopausal patients with hormone receptor (HR) positive BC receiving a non-steroidal aromatase inhibitor were randomly assigned to denosumab or placebo. In this post-hoc analysis, we investigated the potential effects of concomitant statin therapy on recurrence risk of BC, fracture risk and bone mineral density (BMD) using time-dependent Cox proportional hazards models. Sensitivity analyses accounting for immortal time and confounding bias were performed. Results In the analysis of the study population (n=3,420), statin therapy (n=824) was associated with worse disease-free survival (DFS) (HR 1.35, 95%; CI 1.04-1.75; p=0.023). Sensitivity analysis relativized these results (HR 1.22, 95% CI 0.94 - 1.59; p=0.14). While there was no significant effect of lipophilic statins (n=710) on recurrence risk (HR 1.30, 95% CI 0.99 - 1.72; p=0.062), patients on hydrophilic statins (n=87) had worse DFS compared with patients not receiving any statins (HR 2.00, 95% CI 1.09-3.66; p=0.026). This finding was mainly driven by the effect of hydrophilic statins on DFS in the denosumab arm (HR 2.63, 95% CI 1.21 - 5.68; p=0.014). No association between statin use and fracture risk or osteoporosis was observed. Conclusion In this population of early-stage breast cancer patients from a prospective randomized study, an association of hydrophilic statins with increased recurrence risk was observed. According to this retrospective analysis hydrophilic statins may increase recurrence risk especially in patients treated with denosumab. Still, our data need to be interpreted with caution due to their retrospective nature and the low number of patients receiving hydrophilic statins. Therefore, no final conclusion is possible. This hypothesis generating result warrants further exploration. Citation Format: Christoph Minichsdorfer, Thorsten Fuereder, Michael Leutner, Christian F. Singer, Stephanie Kacerovsky-Strobl, Daniel Egle, Richard Greil, Marija Balic, Florian Fitzal, Georg Pfeiler, Sophie Frantal, Rupert A. Bartsch, Michael Gnant. Effect of concomitant statin treatment in postmenopausal patients with hormone-receptor positive early-stage breast cancer receiving adjuvant denosumab or placebo: A post-hoc analysis of ABCSG-18 [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 P1-15-01.