Barros, PatríciaGonçalves, VâniaJordan, PeterMatos, Paulo2026-03-042026-03-042025-11-21http://hdl.handle.net/10400.18/11103Introduction: Breast cancer (BC) is the most common malignant neoplasm among women worldwide and remains a leading cause of cancer-related mortality. It is a heterogeneous disease classified into molecular subtypes with distinct prognostic and therapeutic implications. Luminal A is the most prevalent subtype, characterised by high expression of hormone receptors (oestrogen and progesterone), low proliferation rate, and generally favourable prognosis. However, consistent evidence indicates a significant risk of late recurrence and new neoplastic events, posing challenges for clinical follow-up strategies. Methodology: We analysed genomic data from the TCGA breast cancer cohort (n = 1247) to assess the prognostic value of the BCL6 gene, a transcriptional regulator previously implicated in tumour progression. Data on BCL6 expression, molecular subtyping (PAM50), and overall survival (OS) were retrieved. Results: Although BCL6 expression was globally reduced in tumours compared to normal tissue, it was significantly higher in Luminal A tumours than in other subtypes, with a subgroup (44%) maintaining expression levels similar to normal tissue. Importantly, within the Luminal A subtype, higher BCL6 expression was associated with poorer long term survival (p = 0.041). Discussion: These findings support the potential of BCL6 as a stratification biomarker for the risk of long term neoplasm recurrence within Luminal A breast cancer, with possible implications for tailoring the intensity and duration of clinical follow-up.engBCL-6luminal APrognostic MarkerBreast CancerVias de Transdução de Sinal e Patologias Associadasconference object