Role of resection margins in patients treated with breast conservation surgery.

BACKGROUND: After breast conservation therapy (BCT), margin status is routinely evaluated to select patients who need reexcision. The aim of this study was to investigate how margin status and other clinicopathologic factors correlate with the presence of residual tumor at reexcision.
METHODS: A series of 431 breast cancer patients who underwent BCT followed by reexcision were considered because they had positive or close (< or =3 mm) margins. At univariate and multivariate analysis the frequency of residual tumor in the reexcision specimens was associated with the status and width of resection margins and with a series of other clinicopathologic factors.
RESULTS: Of the 382 evaluable patients, 253 had positive and 129 close margins. Residual tumor was found at reexcision in 51.8% positive-margin patients and 34.1% close-margin patients (P = .001). In the latter group tumor-margin distance (range, 0.08 to 3 mm) was not associated with the incidence of residual tumor (P = .134). On univariate analysis age < or =45 years (P = .006), intraductal histotype (P = .005), size > 2 cm (P = .010), positive axillary nodes (P = .031), and timing of reexcision (P = .044) were significantly associated with a higher frequency of residual tumor. All these factors, except tumor size, maintained a significant predictive value on multivariate analysis.
CONCLUSIONS: In the presence of positive margins, relevant residual disease cannot be ruled out and further surgery is indicated. Close margins do not mandate reexcision because they may indicate either that the tumor has been radically excised or the presence of residual foci of a multifocal tumor, which are usually effectively treated by radiotherapy.