Is Progesterone Receptor a Neglected Feature in Breast Cancer? A Retrospective Study Analysing the Clinicopathological Characteristics of Breast Cancer Based on Progesterone Receptor Status

This study investigates the role of progesterone receptor (PR) in breast cancer, analyzing its associations with clinical and demographic factors in 2,223 Portuguese patients. PR expression correlated with BMI, tumor type, grade, stage, ER, and HER2 status, with PR-negative cases linked to worse outcomes. Findings highlight PR's critical influence on breast cancer prognosis and treatment strategies. Purpose: The aim of this study is to analyse PR independently and its relationship with demographic and clinicopathological information. Introduction: Steroid hormones, particularly estrogen and progesterone, play a crucial role in breast cancer (BC) etiology. Research attention has focused mainly on estrogen while the progesterone impact on breast cancer has yet to be fully uncover. Hormone receptors, including those for estrogen and progesterone, are crucial in BC molecular classification, shaping prognosis and treatment strategies. Beyond its metabolic effects, progesterone and its receptor (PR) have significant clinical implications, impacting clinical outcomes. Materials and Methods: The study comprised 2223 women who were diagnosed with BC at the Comprehensive Cancer Centre in Portugal (IPO-Porto) between 2012 and 2016. Variables, including age at diagnosis, body mass index (BMI), laterality, topographic localization, histological type, differentiation grade, tumor stage, estrogen receptor (ER) and Human Epidermal growth factor Receptor 2 (HER2) expression, were stratified according to the expression of Progesterone Receptor. Statistical analysis included Pearson's Chi-squared test, binary and multinomial regression, and Cox proportional hazard model. Statistical significance was set for P < .05. Results: The results reveal a statistical association between PR and BMI, histological type, differentiation grade, tumour stage, ER and HER2. Progesterone receptor negativity is associated with adverse clinical outcomes, including advanced tumor stages, and diminished overall survival. Conclusion: Further research is needed to elucidate the precise contributions of progesterone to breast cancer progression and to optimize therapeutic approaches for improved patient outcomes.