Cavity margins and lumpectomy margins for pathological assessment: which is superior in breast-conserving surgery?

This prospective cohort study aimed to compare the efficacy of cavity margins (CMs) and lumpectomy margins (LMs) for pathological assessment in breast-conserving surgery.

We assessed the CMs and LMs of 163 breast cancer patients during breast-conserving surgery. We compared and analyzed the positivity rates of CM and LM.

The positivity rate of CM at the case level and individual margin level was 30.7% and 8.0%, respectively. The positivity rate of LM was 12.3%, 33.1%, and 45.4% at the case level and 1.8%, 6.2%, and 9.1% at the individual margin level, when we used the National Surgical Adjuvant Breast and Bowel Project criteria (ink-free), 1 mm-free criteria and 2 mm-free criteria, respectively. The positivity rate of LM with 1 mm-free criteria was similar to that of CM. Delivery of neoadjuvant chemotherapy increased the positivity rate of CM (50.0% versus 25.2%; P < 0.01) but not LM (41.6% versus 30.7%; P > 0.05) at the case level, whereas the positivity rate of CM and LM both increased after neoadjuvant chemotherapy at the margin level (CMs: 15.5% versus 5.6%, P < 0.001; and LMs: 10.7% versus 4.9%, P < 0.001). In univariate and multivariate analysis, delivery of neoadjuvant chemotherapy, higher node-positive stage, and presence of ductal carcinoma in situ component were correlated with positive CM, whereas positive human epidermal growth factor receptor 2 status and higher node-positive stage were associated with positive LM.

Ink-free criteria may be insufficient for LM assessment in breast-conserving surgery, and at least 1 mm width LM is suggested. After the delivery of neoadjuvant chemotherapy, CM assessment should be routinely performed in addition to LM assessment.