Lumpectomy specimen margins are not reliable in predicting residual disease in breast conserving surgery

BackgroundIn breast conserving surgery, the concordance between lumpectomy margin (LM) status and the status of the corresponding lumpectomy cavity remains uncertain.MethodsWe analyzed pathology reports of lumpectomies from 2004 to 2006. We included those which contained both ink-directed LM and complete (≥4) separate corresponding shaved cavity margins (SCMs). SCM pathology was used as a surrogate for lumpectomy cavity status, to determine the predictive value of LM for residual disease.ResultsPathology from 1,201 pairs of LM and SCM from 242 patients was compared. LM status predicted corresponding lumpectomy cavity status with 50.9% sensitivity, 69.5% specificity, 35% positive predictive value, and 81.4% negative predictive value, giving an overall accuracy of 64.9%.ConclusionsOriented LMs are not reliable for predicting lumpectomy cavity status, and therefore not reliable for directing re-excision. Taking complete, oriented SCMs at the time of lumpectomy may improve accuracy compared with traditional LM assessment.