This study (retrospective observational/experimental study) will be conducted in St. John’s Research Institute, Bangalore, India under the LMIC mentor Dr. Jyothi S Prabhu, Faculty, Division of Molecular medicine, St. John’s Research Institute.This project aims to investigate the unique tumor micro-environment (TME) of postpartum breast cancer (PPBC) samples already collected from women under 45 years of age using archived FFPE (formalin fixed paraffin embedded) tissue and clinical data. Treatment-naïve primary tumor samples will be selected from an existing breast cancer cohort. Spatial profiling will be performed to characterize immune and stromal cell distribution within the TME. Clinical, reproductive, and pathological data will be integrated to identify PPBC-specific features. Key biomarkers identified through spatial profiling will be validated using multiplex immuno-histochemistry (mIHC). Comparative analysis will be conducted between PPBC and non-PPBC cases to uncover differentially enriched immune pathways or cell types. Long-term follow-up data will be used to assess the prognostic significance of these biomarkers in stratifying high-risk patients. Only de-identified data will be securely shared with the U.S. mentor as part of this NIH Fogarty INSIGHT Fellowship. The study adheres strictly to ethical guidelines and poses minimal risk to participants as it is retrospective study performed only on the already collected tissue samples.