The Relationship of Breast Density and Positive Lumpectomy Margins

A positive lumpectomy margin after breast-conserving surgery (BCS) is a significant predictor for ipsilateral cancer recurrence. The MarginProbe, a Food and Drug Administration (FDA)-approved device for intraoperative assessment of lumpectomy margins, is associated with a reduction in re-excision surgery. This study aimed to evaluate the relationship of mammographic breast density (MBD) and clinicopathologic characteristics with margin status in women undergoing BCS with the MarginProbe.

The institutional database was queried for patients with breast cancer who had BCS with the MarginProbe from 2013 to 2017. Clinicopathologic characteristics were collected. The study defined MBD as less dense (Breast Imaging Reporting and Data System [BI-RADS] A and B) and more dense (BI-RADS C and D). A positive margin was defined as smaller than 1 mm. Pearson Chi square and uni- and multivariate logistic regression were performed.

Of 1734 patients, 341 met the study criteria. The median patient age was 63 years. The patients with higher mammographic density were younger (p < 0.0001) and had a lower body mass index (BMI) (p < 0.0001). The patients with higher MBD were more likely to present with a palpable mass (p = 0.0360). Of the 341 patients, 135 (39.6%) had one or more positive margins on the main specimen, and 101 (74.8%) were converted to final negative margins after the MarginProbe directed re-excisions. Positive final margins were associated with larger tumor size (p = 0.0242) and more advanced stage of disease at diagnosis (p = 0.0255).

In this study of patients undergoing BCS, breast density was not correlated with the likelihood of a positive margin. The presence of positive final lumpectomy margins was associated with older age and more extensive disease.