Correlations Between mammographic breast density and outcome after neoadjuvant chemotherapy in patients with locally advanced breast cancer.

Abstract

Abstract Background – The inverse association between high mammographic breast density (MBD) and pathologic complete response (pCR), following neoadjuvant chemotherapy (NAC) for early breast cancer (BC), implicates high MBD in chemotherapy resistance. However, no trial has extended the relationship beyond pCR to overall survival. Aim - To validate the relationship between MBD and pCR in patients undergoing NAC for early BC. To assess the relation of MBD with clinical complete response (cCR), relapse-free (RFS) and BC-specific survival (BCSS). Methods – MBD was measured in contralateral mammograms in 127 women before NAC, using Cumulus software. 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. Mean MBD was higher in those not undergoing cCR (p = 0.041) and relapsing patients (p = 0.041) but did not vary by pCR or BC-deaths. As a dichotomous variable, high MBD corresponded to lower cCR (40 v 58%, p = 0.027). No difference was seen between high and low MBD cohorts 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). A planned analysis in obese patients demonstrated high MBD was associated with lower pCR (0% v 28.1%, p = 0.036) and higher relapse rates (56% v 28%, p = 0.063). No such relationship was observed in non-obese patients. Conclusion – high MBD associated with lower cCR and higher relapse but not with pCR or BC death. Further analysis, including by body mass index, is warranted.