The adequacy of breast-conserving surgery (BCS) for invasive or in situ disease is largely determined by the final surgical margins. Although margin status is associated with various clinicopathologic features, the influence of resident involvement remains controversial.

Patients who underwent BCS for malignancy from 2009 to 2012 were identified. The effects of various clinicopathologic characteristics and resident involvement were evaluated.

Of the 502 cases performed, a resident assisted with most surgeries (95%). The overall rate of positive margins was 30%, which was not associated with resident involvement. Interns assisting from July to September had significantly lower rates of positive margins. Margins were more likely to be positive following any given resident's first 3 cases on their breast rotation than throughout the remainder of their rotation.

Although resident level alone does not influence the adequacy of BCS, experience gained over time does appear to be associated with lower rates of positive margins.