Abstract 3602: The association between longitudinal lipid trajectories and all-cause mortality in breast cancer survivors: A population-based study

Abstract Background: Given breast cancer is the second leading cause of cancer-related death in women, it is important to identify breast cancer patients at high risk of mortality. Lipid levels before and after diagnosis may be key indicators for overall health and prognostic outcomes for breast cancer patients. This study aimed to identify distinct lipid trajectories in those diagnosed with breast cancer and examined their association with all-cause mortality. Methods: This population-based retrospective cohort study included females diagnosed with incident breast cancer who survived at least five years after diagnosis (i.e., breast cancer survivors). Total cholesterol, low-density lipoprotein (LDL), high-density lipoprotein (HDL), and triglycerides (mmol/L) were used to develop trajectory patterns for each lipid through group-based trajectory modelling. Cox proportional hazards models estimated hazard ratios (HR) and 95% confidence intervals (CI) of all-cause mortality by lipid trajectories. Results: The study included 32, 537 female breast cancer survivors. Approximately 30% of the study population lipid levels within recommended ranges before and after a breast cancer diagnosis (moderate-stable trajectory). Nearly 10% of the population had very low lipids before and after a breast cancer diagnosis (very low-stable trajectory); this pattern was associated with an increased risk of all-cause mortality for total cholesterol (HR 1.38, 95%CI 1.16, 1.66), LDL (HR 1.24, 95%CI 1.04, 1.49), and HDL (HR 1.20, 95%CI 1.02, 1.40), compared to the moderate-stable trajectory. Approximately 5-6% had very high total cholesterol or LDL that rapidly declined after a breast cancer diagnosis (very high-declining trajectory); this pattern was associated with an increased risk of all-cause mortality compared to a moderate-stable trajectory (HR 1.59, 95%CI 1.23, 2.05; HR 1.40, 95%CI 1.09, 1.81, respectively). The association between lipid trajectories and all-cause mortality did not significantly differ by lipid-lowering agent use, suggesting pharmacologic management did not impact the findings. However, those not on a lipid-lowering agent had a mortality risk of higher magnitude than those on pharmacologic intervention. Conclusions: Breast cancer patients with very low lipids before and after diagnosis, and patients with very high lipids that rapidly decline to low levels after diagnosis were identified as subgroups at high risk of mortality. These findings highlight the importance of considering longitudinal, repeat lipid measures to improve long-term outcomes in this population. Citation Format: Shana Jean Kim, Vanessa De Rubeis, Brendan T. Smith, Husam Abdel-Qadir, Jennifer D. Brooks. The association between longitudinal lipid trajectories and all-cause mortality in breast cancer survivors: A population-based study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 3602.