Since clinical trials have demonstrated that breast conservation is safe and effective for treatment of invasive breast cancer, there has been considerable disagreement and controversy about what constitutes an acceptable margin in breast cancer. Dogmatic adherence to a set margin for all patients may cause a higher mastectomy rate than necessary, and thus it is important to understand how various clinical and pathologic factors affect local recurrence and outcome. This review discusses that controversy, as well as what factors should be considered when evaluating patients on an individual basis.
