Influence of Surgical Margins on the Outcome of Breast Cancer Patients: A Retrospective Analysis

Breast-conserving surgery has become the preferred treatment for early breast cancer. Yet the question of what constitutes a 'safe margin', in terms of impact on patient outcome, remains unanswered. Our aim was to address this knowledge gap by determining the prevalence of positive and narrow margins after breast-conserving surgery, and evaluating how margin status impacted local recurrence and overall survival. We collected data about all women who underwent breast-conserving cancer surgery in our department between 2002 and 2011, focusing on patient and tumor characteristics, the distance from the tumor to the surgical margin, therapies administered, and outcome (measured in terms of local recurrence and overall survival). Data were analyzed by R (version 3.0.1), considering p < 0.05 as significant. Multivariate analyses were also performed. Of 1,192 women who received breast-conserving surgery, 264 were considered for widening; 111 of these patients had positive margins and 153 narrow (where narrow was defined as less than 5 mm). Widening was performed for 38 % of these patients (99/264) and mastectomy for 27 % (70/264), while 36 % (95/264) had no further surgery and were simply followed-up. Our multivariate analysis confirmed that local tumor recurrence and overall survival were not significantly influenced by margin status, either at initial surgery, or (for those patients with initially positive margins) at secondary margin-widening surgery. However, the following were found to be significantly correlated with local recurrence: tumor multifocality, high expression of Ki-67/Mib-1, comedo-like necrosis, and non-axillary lymph node positivity (p < 0.05). We found the status of resection margins and the management of infiltrated or narrow margins to have no significant influence on local tumor recurrence rates or on overall patient survival. Instead, biological factors connected with tumor aggressiveness seem to play the most important role in breast cancer prognosis, independent of surgical radicality.