Clinical Outcomes of HER2-Positive Advanced Breast Cancer in a Resource-Constrained Setting: A Retrospective Cohort Study

Advanced breast cancer (ABC) constitutes an incurable illness, exhibiting a median overall survival (OS) of roughly 3 years, a figure observed even within high-income settings. Survival has been prolonged by oncological therapies, particularly in hormone receptor–positive and HER2-positive disease; however, the availability of novel agents across Latin American (LATAM) nations remains constrained. An assessment of the influence of sequencing two therapeutic lines among Peruvian individuals diagnosed with HER2-positive ABC at a single public facility was conducted. The initial, first-line (1L) regimen combined trastuzumab with chemotherapy (CT, including taxanes), followed by a second-line (2L) regimen of lapatinib plus capecitabine. This study is a retrospective analysis that investigates clinico-pathological attributes (including blood biomarkers) derived from medical documentation of HER2-positive ABC patients managed at a public oncological center in Peru, along with their relationship to survival recorded from 2020 through 2022. Effectiveness was gauged by OS and progression-free survival (PFS). A commentary was incorporated on the impact of clinicopathological parameters on OS, including results from 2L “long-term responder” subjects (who attained a response to 2L treatment lasting ⩾ 6 months), as well as an appraisal of blood biomarkers. Treatment sequencing extends OS in HER2-positive ABC patients, with a median OS of 34 months. The effect is amplified within the long-term responder group (37 months), particularly for those free from central nervous system (CNS) disease, relative to individuals harboring CNS metastases (51 vs 34 months). Blood biomarkers failed to emerge as prognostic factors for either PFS or OS. Treatment sequencing has been shown to extend OS among LATAM patients with HER2-positive ABC. The present investigation uncovered no prognostic blood biomarkers. Such findings may shape the criteria for selecting patients for treatment sequencing in settings where innovative oncological drugs are not fully available.