SAN FRANCISCO – Breast density is an independent risk factor for positive lumpectomy margins, pointing to a need for better methods of intraoperative margin assessment, researchers contend.
Data from a randomized clinical trial evaluating intraoperative tumor margin detection techniques indicate that for every increase in breast density category, the risk of positive margins on the main lumpectomy specimen increases by 46%, reported Dr. Tanir Allweis of Hebrew University Medical Center in Jerusalem, Israel.
“The use of newer technology and advanced techniques for intraoperative margin assessment, more extensive preop evaluation of these patients with MRI, or more liberal reshaving during the time of initial lumpectomy might be able to decrease the rate of reoperations in women with dense breasts,” Dr. Allweis said in an interview at the 2015 ASCO Breast Cancer Symposium.
She and colleague Dr. Freya Schnabel of New York University Langone Medical Center in New York City reviewed data on women enrolled in a clinical trial in which patients were randomized to lumpectomy with standard margin assessment or the use of an intraoperative radiofrequency spectroscopy device (MarginProbe). Of the 664 women enrolled in the trial, information on breast density was available for 450, and these women were included in the current study.The authors looked at data on breast density, patient and tumor characteristics, and the margin status of the primary lumpectomy specimen prior to randomization (that is, before the use of the device or the surgeon’s customary margin assessment technique).
They defined positive margins as ink on tumor. Breast density was rated on a scale of 1 (mostly fatty) to 4 (extremely dense) according to the American College of Radiology BI-RADS breast density descriptors.
Higher breast density was associated with younger age at diagnosis, lower body mass index, smaller breasts, and smaller specimen volume. Women with dense breasts were more likely to have had preoperative MRI (odds ratio [OR] 2. P less than .0001).
Each increase in breast density category was associated with an OR of 1.46 for positive margins in the main lumpectomy specimen. Thus, while women with mostly fatty breasts had a 14% risk for positive margins, women with extremely dense breasts had a 40% risk for positive margins.
The association between breast density and margin positivity remained significant after the researchers controlled for age, BMI, breast volume, and specimen volume (adjusted OR 1.39-1.52, P less than .036).
The investigators plan to explore whether the tumors in denser breasts may be larger than initially suspected because of the documented difficulties in imaging extremely dense tissues.
“These results suggest that the use of adjunctive methods for intraoperative margin assessment may be particularly helpful in this patient population. Further research will be important to clarify the benefit of various methods to decrease the rate for reexcision procedures in patients with increased breast density,” the investigators wrote in a poster presented at the symposium.