RNA-seq very young breast cancer

Breast cancer predominantly affects women over 50, but about 5% of cases occur in very young women, aged 35 or younger, presenting significant clinical challenges and poorer outcomes. This study evaluated molecular differences between very young breast cancer (VYBC) and old breast cancer (OBC) patients, focusing on the hormone receptor-positive/HER2-negative (HR+/HER2-) subtype and therapeutic implications. Transcriptomic analysis of 49 untreated primary tumors (22 VYBC and 27 OBC) revealed distinct molecular profiles. In the HR+/HER2- subtype, VYBC tumors showed increased heterogeneity and upregulation of genes related to proliferation, chromosome instability, and immune activation compared to OBC. Deconvolution algorithms confirmed elevated immune cell infiltration and overexpression of immunological checkpoints, indicating a "hot" tumor microenvironment. Histological validation demonstrated significantly higher tumor-infiltrating lymphocytes and tertiary lymphoid structures in VYBC, supporting the potential efficacy of immunotherapy in this subgroup. These findings underscore the biological complexity and highlight opportunities for personalized therapeutic strategies for HR+/HER2- VYBC.