Compromised margins following mastectomy for stage I-III invasive breast cancer

We investigated factors associated with positive margins following mastectomy and the impact on outcomes.

We identified 240 patients with stage I-III invasive breast cancer who underwent mastectomy from 1999 to 2009. Data included patient and tumor characteristics, pathologic margin assessment, and outcomes. Margin positivity was defined as the presence of in situ or invasive malignancy at any margin. Descriptive statistics were used for data summary and were compared using χ(2).

Of the 240 patients, 132 (55%) had a simple mastectomy with sentinel lymph node biopsy and 108 (45%) had a modified radical mastectomy. Overall, 21 patients (9%) had positive margins, including 12 (57%) with one positive margin, 3 (14%) with two positive margins, and 6 (29%) with three or more positive margins. The most commonly affected margin was the deep margin (48% of patients). Eight of the 21 patients (38%) received adjuvant chest wall irradiation. There were no differences between patients who had a positive margin and those who did not with respect to patient age, race, percentage of in situ component, tumor size, tumor grade, lymphovascular invasion, or immunostain profile (P > 0.05 for all). None of the patients with positive margins experienced a local recurrence.

Positive margins following mastectomy occurred in nearly 10% of our patients. No specific patient or tumor characteristics predicted a risk for having a positive margin. Despite the finding that only approximately 40% of patients received adjuvant radiation in the setting of a positive margin, no local recurrences have been observed.