The Effect of Margin Width on Local Recurrence after Breast Conservation Therapy

ABSTRACT

PURPOSE: The association between the margin status and the risk of a local recurrence (LR) after breast conservation therapy (BCT) is controversial. In addition, the width of the resection margin that minimizes the risk of LR is unknown. This study examined the interaction between the margin width, tumor characteristics, and adjuvant systemic therapy on the risk of LR after BCT. METHODS: The records of 348 women with T1 and T2 breast cancers, who were treated with BCT between 1997 and 2004, were reviewed. Patients who underwent a re-excision with a positive margin were excluded. The margin was classified as close (5mm tumor-free margin). Various clinical and pathologic factors were analyzed as potential prognostic factors for LR in addition to the margin width. RESULTS: The rate of LR for all patients after a mean follow-up of 37.2 months was 3.7% (13/348). The LR rates were significantly associated with young age (2 cm, P=0.021) and negative hormone receptor (P=0.032). A positive axillary lymph node, the presence of EIC, high histological tumor grade, high proliferative index (Ki-67), the presence of lymphovascular invasion, the over-expression of c-erbB2 and the expression of p53 was not significant. Systemic adjuvant therapy was not associated with a lower rate of LR in both groups. The final resection margins were close in 30 patients (8.6%) and negative in 318 patients (91.4%). The rates of LR by the margin width were 6.7% (2/30) for close margins and 3.5% (11/318) for negative margins. There were no significant differences in the rate of LR according to the margin width. The rate of LR in patients with a 1 mm tumor-free margin width was 13.3% (2/15). Moreover, there is a tendency for an increase in the LR with a 1 mm tumor-free margin than with a margin width >1 mm (P=0.046). CONCLUSION: According to this study, if the margin is tumor-free, a close resection margin (< or =5 mm) is not associated with an increased rate of LR in BCT. However, a high rate of LR can be expected in patients with 1 mm margins.