Predictive factors for residual disease in re-excision specimens after breast-conserving surgery.

Local recurrence is an issue of concern after breast-conserving therapy and removing the primary tumor with negative surgical margins is the most important determinant of local recurrence. However, some patients with positive margins after initial surgery will have no residual tumor in the re-excision specimen. To avoid unnecessary re-excisions, factors predicting residual disease in re-excision material should be determined. This study aimed to determine the predictive factors for residual disease in the re-excision material in a homogeneous group of patients with positive margins and only invasive ductal carcinoma. Breast cancer patients treated between 2005 and 2008 with breast-conserving surgery and subsequent re-excisions due to positive surgical margins after initial surgery were included in the study. Patients were divided into two groups as those with and without residual disease in the re-excision material. One hundred and four breast cancer patients were included in the study. Forty-seven patients (45.2%) had residual tumor in re-excision specimen. Patient characteristics such as age (p = 0.42) and physical findings (p = 1.0) and specimen volume (p = 0.24), tumor grade (p = 0.33), estrogen (p = 1.0), and progesterone (p = 0.37) receptor status, axillary lymph node metastases (p = 0.16), extensive intraductal component (p = 0.8), and lymphovascular invasion (p = 0.064) were found as insignificant factors for predicting residual tumor. Large tumor size (>3 cm) (p = 0.026), human epidermal growth factor receptor2 (HER2) positivity (p = 0.013), and tumor to specimen volume ratio of >70% (p = 0.002) significantly increased the probability of finding residual disease after re-excision. In multivariate analysis, HER2 positivity (p = 0.046) and tumor to specimen volume ratio of >70% (p = 0.006) independently predicted the presence of residual disease. As a result, in patients with HER2 positive tumors larger than 3 cm, larger volume of breast tissue around the tumor should be removed to decrease the number of re-excisions due to positive surgical margins.