highly significantp = 0.0001
Obtaining a tumor-free surgical margin decreases the incidence of a local recurrence (LR) of the primary tumor.[ 18 ] There are various risk factors associated with a positive margin, among them are: The extent of excision, age, large tumor size, multifocality, lobular histological type, and the number of positive lymph nodes.[ 19 ] In 30 of 34 reviewed studies, persistent microscopic inadequate (R1) or macroscopic inadequate (R2) surgical margins were highly significant for LR compared to the negative margin (p = 0.0001).[ 20 ] Microscopic disease resulting from a positive margin is more problematic because theoretically, cancer in the relatively hypoxic environment of the lumpectomy scar bed will be resistant to radiation therapy.[ 21 ] Furthermore, the inability to achieve negative margins may be a marker of an excessive tumor burden in the treated breast.