1052 – Pharmacoeconomic analysis of second-line hormone therapy in advanced breast cancer in Brazil (2020-2025)

Abstract

Introduction: Endocrine resistance, operationalized as second-line endocrine therapy use in breast cancer, increases
healthcare expenditure, yet its economic impact remains poorly characterized. This study evaluates the financial asymmetry between first- and second-line therapies in the Brazilian Public Health System (SUS), to quantify the economic
burden of resistance.
Methods: Ecological, retrospective study following STROBE reporting guidelines using the DATASUS outpatient database
(SIA-SUS/Oncology Panel) from 2020-2025. Procedure volumes and expenditures were analyzed for first (0304020346) and
second-line therapies (0304020338/0304020354) per procedure. Trends were assessed using Joinpoint regression (Annual
Percent Change, APC, with 95% confidence intervals). Differences in median cost per procedure (CPP), adjusted for inflation, were evaluated with the Mann-Whitney U test. A counterfactual analysis applied first-line median cost to secondline volume to estimate incremental expenditure.
Results: In total, 1,330,175 procedures were analyzed. First-line therapies accounted for 59.0% of the overall volume
(n=784,992) and 27.6% of the total healthcare expenditures (R$ 62.6 million), while second-line therapies represented
41.0% (n=545,183) yet consumed 72.4% (R$ 164.3 million). Median CPP was R$ 79.75 vs R$ 301.51 (p=0.003). First-line use
increased significantly (APC: +5.83%/year; 95%CI 4.47–7.23; p<0.001), while second-line therapies showed slower growth
(APC: +1.84%/year; 95%CI 0.17–3.58; p=0.033). The incremental expenditure associated with second-line therapy was
R$ 120.9 million (mean annual: R$ 20.2M).
Conclusion: Endocrine resistance imposes a substantial and disproportionate economic burden on the Brazilian Public
Health System (SUS), with second-line therapies consuming most expenditures despite lower procedural volume. The
incremental cost of R$ 120.9 million reflects inefficiencies related to disease progression. These findings support prioritizing strategies to delay resistance, including optimization of first-line endocrine therapy, improved adherence, and costeffective incorporation of novel agents. Interventions that prolong first-line effectiveness may reduce expenditures and
improve sustainability in resource-constrained settings.
Ethics: Public data.