RT Journal Article T1 Added Value of Serum Hormone Measurements in Risk Prediction Models for Breast Cancer for Women Not Using Exogenous Hormones: Results from the EPIC Cohort. A1 Hüsing, Anika A1 Fortner, Renée T A1 Kühn, Tilman A1 Overvad, Kim A1 Tjønneland, Anne A1 Olsen, Anja A1 Boutron-Ruault, Marie-Christine A1 Severi, Gianluca A1 Fournier, Agnes A1 Boeing, Heiner A1 Trichopoulou, Antonia A1 Benetou, Vassiliki A1 Orfanos, Philippos A1 Masala, Giovanna A1 Pala, Valeria A1 Tumino, Rosario A1 Fasanelli, Francesca A1 Panico, Salvatore A1 Bueno de Mesquita, H Bas A1 Peeters, Petra H A1 van Gills, Carla H A1 Quirós, J Ramón A1 Agudo, Antonio A1 Sanchez-Perez, Maria-Jose A1 Chirlaque, Maria-Dolores A1 Barricarte, Aurelio A1 Amiano, Pilar A1 Khaw, Kay-Tee A1 Travis, Ruth C A1 Dossus, Laure A1 Li, Kuanrong A1 Ferrari, Pietro A1 Merritt, Melissa A A1 Tzoulaki, Ioanna A1 Riboli, Elio A1 Kaaks, Rudolf AB Purpose: Circulating hormone concentrations are associated with breast cancer risk, with well-established associations for postmenopausal women. Biomarkers may represent minimally invasive measures to improve risk prediction models.Experimental Design: We evaluated improvements in discrimination gained by adding serum biomarker concentrations to risk estimates derived from risk prediction models developed by Gail and colleagues and Pfeiffer and colleagues using a nested case-control study within the EPIC cohort, including 1,217 breast cancer cases and 1,976 matched controls. Participants were pre- or postmenopausal at blood collection. Circulating sex steroids, prolactin, insulin-like growth factor (IGF) I, IGF-binding protein 3, and sex hormone-binding globulin (SHBG) were evaluated using backward elimination separately in women pre- and postmenopausal at blood collection. Improvement in discrimination was evaluated as the change in concordance statistic (C-statistic) from a modified Gail or Pfeiffer risk score alone versus models, including the biomarkers and risk score. Internal validation with bootstrapping (1,000-fold) was used to adjust for overfitting.Results: Among women postmenopausal at blood collection, estradiol, testosterone, and SHBG were selected into the prediction models. For breast cancer overall, model discrimination after including biomarkers was 5.3 percentage points higher than the modified Gail model alone, and 3.4 percentage points higher than the Pfeiffer model alone, after accounting for overfitting. Discrimination was more markedly improved for estrogen receptor-positive disease (percentage point change in C-statistic: 7.2, Gail; 4.8, Pfeiffer). We observed no improvement in discrimination among women premenopausal at blood collection.Conclusions: Integration of hormone measurements in clinical risk prediction models may represent a strategy to improve breast cancer risk stratification. Clin Cancer Res; 23(15); 4181-9. ©2017 AACR. YR 2017 FD 2017-02-28 LK http://hdl.handle.net/10668/10916 UL http://hdl.handle.net/10668/10916 LA en DS RISalud RD Aug 8, 2025