Predictors of Residual Disease After Breast Conservation Surgery

Introduction. Breast-conserving therapy is the standard of care for early-stage breast cancer. In the era of multimodality therapy, the debate on the value of revision surgery for compromised margins continues, and high re-excision rates persist despite updated guidelines. Our study sought to identify the local re-excision rate for compromised margins after lumpectomy, and identify predictors of residual disease at re-excision. Methods. This population-based retrospective cohort study included women with breast cancer who underwent a lumpectomy between 2009 and 2012 in Manitoba, with close (<= 2 mm) or positive margins that led to re-excision. Patient demographics and tumor characteristics were identified through provincial cancer registries and chart reviews. For patients with invasive cancer, the six anatomical margins were reported for margin status, width, and pathology type at the margin. Results. Of the 2494 patients identified, 556 women underwent re-excision, yielding a re-excision rate of 22.29%. Of our 311 patients with invasive cancer who underwent re-excision, 62.7% had residual disease identified on revision. On univariable analysis, the size and grade of the invasive component, nodal stage, and the number of positive margins were associated with residual disease on re-excision (p < 0.05). With the exception of nodal stage, the same variables remained statistically significant on multivariable analysis. Conclusions. Our results suggest that even in the absence of 'no ink on tumor', the cancer size and grade in lumpectomy specimens are high-risk factors for residual disease, and this subgroup of patients may benefit from re-excision. Long-term follow-up of this cohort is required to determine their risk of recurrence after adjuvant treatment.