Introduction
Neoadjuvant chemotherapy (NAC) was originally one of the standard treatments for local advanced breast cancer. However, NAC is now increasingly being used among patients with early-stage breast cancer, because it can reduce the tumor size and convert patients who were initially candidates for mastectomy to be candidates for breast conserving surgery (BCS)1,2Additionally, NAC can eliminate metastatic disease in reginal lymph nodes which may change the surgical strategy of the axilla. It is established that a negative margin should be obtained when performing breast-conserving therapy. Compared with negative margins (>2mm), positive margins (defined as ink on ductal carcinoma in situ or invasive carcinoma) lead to a twofold increase in the risk of local recurrence3. To date, several factors have been studied to be associated with the increased risk of local recurrence after breast-conserving surgery, including lymphovascular invasion, large tumor size, positive nodal status, extensive intradutal component, close or involved margin status, negative hormone receptor status4. Atypical hyperplasia (AH) of the breast which can be categorized as atypical ductal hyperplasia (ADH) and atypical lobular hyperplasia (ALH), is a premalignant lesion, refers to abnormal epithelial proliferative breast lesions that are not qualitatively or quantitatively abnormal enough to be classified as carcinoma in situ5. It has been established that patients with AH on breast biopsy of benign lesions have an approximate four-fold increased risk of later breast cancer6,7. However, whether AH can also lead to increased local recurrence in patients underwent breast-conserving surgery remains unknown, especially in patients who have received NAC. Thus far, several studies have explored the issue of whether AH at margins of breast conserving surgery leads to increased local recurrence in the ipsilateral breast, and their conclusions were contradictory8-10. Lennington et al. found that ADH is often located at the periphery of ductal carcinoma in situ (DCIS)11, thus ADH identified at the margin of a BCS specimen may represent DCIS component is already very close to the tumor margin. And close margin may be related to higher local recurrence of the breast4. Therefore, it needs to be further investigated whether AH at margins is associated with local recurrence of breast cancer. To address this, our group previously reported a series of 244 breast cancer patients without NAC treated with BCS between 2009 and 201112. We found that patients with AH at the margins experienced the same local control as those without AH. However, patients treated with NAC were excluded from our previous study. So far, there is no study to investigate the impact of atypical hyperplasia at margins on local recurrence and long-term survival outcomes in the NAC population. Therefore, the aim of the present study was to evaluate the impact of atypical hyperplasia at the surgical margins on the local recurrence and survival outcomes in breast cancer patients treated with NAC and BCS.