Pre-treatment imaging and pathology characteristics of invasive breast cancers of limited extent: potential relevance for MRI-guided localized therapy.

Background And Purpose: Identifying breast cancers of limited extent (BCLE) is becoming increasingly important, especially for (image guided) minimally invasive therapy and partial breast irradiation. The purpose of this study is to establish characteristics at functional imaging and pathology associated with invasive BCLE.

Materials And Methods: Seventy-five patients (77 breasts) with invasive breast cancer were prospectively included. Excision specimens were processed using complete embedding. Microscopic findings were reconstructed and correlated with contrast-enhanced MRI. Tumors were stratified by absence or presence of occult disease ≥10 mm from the MRI-visible lesion: BCLE and non-BCLE, respectively. Imaging and pathology characteristics were evaluated for their ability to discriminate between BCLE and non-BCLE. Multivariate binary logistic regression was employed to create a prediction model for BCLE.

Results: At univariate analysis, imaging as well as pathology characteristics were indicative for BCLE (39/77=51%). At multivariate analysis, a mass on mammography, the absence of tumor washout, positive ER and low quantity of DCIS in the index tumor retained significance (area under ROC curve=0.87).

Conclusions: Pre-treatment assessment of mammography findings, MRI washout kinetics, ER status and quantity of DCIS in the index tumor has the potential to accurately identify BCLE.