Factors predicting residual disease on re-excision after breast conserving surgery

Abstract

Introduction: Breast conserving surgery is the standard of care for early breast cancer, however in a quarter of patients, satisfactory margins are not achieved, usually leading to re-excision. Residual disease is found in less than half of these re-excisions, leading to increased morbidity, poorer cosmesis and increased cost, possibly with no oncological benefit. Our study aimed to identify a group of patients with unsatisfactory margins but a low risk of residual disease, who may be able to avoid re-excision.

Methods and materials: All patients from our unit undergoing re-excision for unsatisfactory margins after breast conserving surgery between January 2013 and October 2019 were identified. Pathological factors predicting residual disease were investigated using univariable and multivariable analysis.

Results: 220 patients were included. 90 (41 %) had residual disease. Residual disease was more likely in those having mastectomy than cavity shaves (61 % vs 32 %, p < 0.0001). Residual disease increased in a linear fashion with number of involved margins and with increasing tumour size. Tumour size <20 mm (p = 0.045), a pathological to radiological tumour size ratio less than 1.5 (p < 0.0001) and disease-free cavity shaves taken at initial surgery (p = 0.041) were all independent predictors of a low chance of residual disease on multivariable analysis. Patients with all three factors had a 14 % chance of residual disease.

Conclusions: More than half of patients undergo potentially unnecessary re-excision, and patients with small, radiologically obvious tumours are less likely to have residual disease. The decision on re-excision should include these factors in addition to the margin status.

Keywords: Breast cancer; Breast conserving surgery; Lumpectomy; Margin; Re-excision; Recurrence; Residual cancer; Residual disease; Wide local excision.