In this study, we investigated FGFR1 gene and protein and FGF ligand expression in paired tumor-adjacent and tumor tissues in relation to MBD and tumor characteristics by making use of a population-based prospective screening cohort, The Karolinska Mammography Project for Risk Prediction of Breast Cancer (KARMA) cohort, with the aim of contributing to bridge the knowledge gaps in the MBD–breast cancer association. The gene discussed is FGFR1; the disease is breast carcinoma.