Excessive resections in breast-conserving surgery: a retrospective multicentre study.

The main determinant of cosmetic outcomes following breast-conserving surgery (BCS) for breast cancer is the volume of resection. The importance of achieving optimal oncological control may lead to an unnecessarily large resection of breast tissue. The aim of this study is to evaluate excess resection volume in BCS for cancer by determining a calculated resection ratio (CRR). This retrospective study was conducted in four affiliated institutions and involved 726 consecutive patients with T1-T2 invasive breast cancer treated by BCS between January 2006 and 2009. The pathology reports were reviewed for tumor palpability, tumor size, surgical specimen size, and oncological margin status. The optimal resection volume (ORV) was defined as the spherical tumor volume with an added 1.0 cm margin of healthy breast tissue. The total resection volume (TRV) was defined as the ellipsoid volume of the surgical specimen. CRR was determined by dividing the TRV by the ORV. Of all tumors, 72% (525/726) were palpable, and 28% (201/726) were nonpalpable. The tumor stage was T1 in 492 patients (67.8%) and T2 in 234 patients (32.2%). The median CRR was 2.5 (0.01-42.93). Margin status was positive or focally positive in 153 patients (21.1%). Lower tumor stage was associated with a higher CRR (factor 0.61 [p < 0.0001] and a lower positive margin rate [p = 0.064]). Accordingly, the median CRR of the nonpalpable lesions was higher than that of the palpable lesions (3.1 and 2.2, respectively; p < 0.01), and the involved margin rate was lower (17.4% and 22.5%, respectively; p = 0.13). Of patients with a CRR >4.0, 10.7% still had tumor involved margins. This study clearly shows that BCS is associated with excessive resection of healthy breast tissue while clear margins are not assured. Surgical factors should be modified to improve surgical accuracy.