Abstract PO2-23-10: Obesity May Modulate the Relationship Between High Mammographic Breast Density and Neoadjuvant Chemoresistance in Early Breast Cancer

Abstract

Abstract Background - An inverse association has been described in a number of studies between mammographic breast density (MBD) and pathologic complete response (pCR) following neoadjuvant chemotherapy (NAC) for early breast cancer (BC), implicating high MBD in chemotherapy resistance. However, this effect has not been seen in all there is a paucity of data exploring whether this relationship extends the relationship beyond pCR to overall survival. This study aims to validate the relationship between MBD and pCR in patients undergoing NAC for early BC as well as to assess the relation of MBD with clinical complete response (cCR), relapse-free (RFS) and BC-specific survival (BCSS). Further, this study examines these associations stratified by body mass index (BMI). Methods - MBD was measured in contralateral mammograms in 127 women before NAC, using Cumulus software. As the study spanned the transition period from film to digital mammography, film mammograms were digitised using a high-powered scanner and processed full-field digital mammograms were extracted from the imaging storage facility. Basic patient, tumour and treatment demographics were collated including BMI. Percent dense area (PDA) was correlated with patient and tumour characteristics, short-term (pCR/cCR incidences), and long-term chemotherapy outcomes (RFS and BCSS). Results - Overall rates of cCR and pCR of 49% and 21% were observed across the whole cohort. Mean PDA was higher in those not undergoing cCR (p=0.041) and relapsing patients (p=0.041) but did not significantly vary by pCR or BC-deaths. As a dichotomous variable, high PDA relative to low PDA corresponded to lower cCR (40 v 58%, p=0.027), but no significant difference was seen for pCR (17.5 v 25.0%, p=0.15), BC relapse (38 v 30%, p=0.15) or BC-death (32 v 25%, p=0.20). High PDA (relative to low PDA) in patients with obesity (BMI >30kg/m2) was associated with lower pCR (0% v 28.1%, p=0.036) and numerically higher relapse rates (56% v 28%, p=0.063) and breast cancer deaths (56 v 28%, p=0.071. No such relationship was observed in patients with a BMI< 30kg/m2. Conclusion - Higher MBD associated with lower cCR and higher relapse but not with pCR or BC death. The inferior outcomes with high MBD were confined to patients with obesity in our study. Further analysis of the relationship between MBD and outcomes, including by BMI, is warranted. Citation Format: Andrew Redfern, Veenoo Agarwal, Ellie Darcey, Lisa Spalding, Hilary Martin, Jennifer Stone. Obesity May Modulate the Relationship Between High Mammographic Breast Density and Neoadjuvant Chemoresistance in Early Breast Cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO2-23-10.