Cavity Shaving Reduces Involved Margins and Reinterventions Without Increasing Costs in Breast-Conserving Surgery: A Propensity Score-Matched Study.

BACKGROUND: Currently, reinterventions for involved margins after breast-conserving surgery remain common. The aim of this study was to assess the capability of the cavity shave margins (CSM) technique to reduce positive margin rates and reoperations compared with simple lumpectomy (SL). The impact of CSM on the various biological portraits of breast cancer and costs were also investigated.

METHODS: A retrospective review of 976 consecutive patients from a single center was performed; 164 patients underwent SL and 812 received CSM. All patients were treated with an oncoplastic approach. and involved margins and reoperations were compared for each group. To avoid selection bias, propensity score-matched analysis was performed before applying a logistic regression model. Main outcomes were reanalyzed for each biological portrait, and surgery and hospitalization costs for SL and CSM were compared.

RESULTS: Clear margins were found in 98.3% of patients in the CSM group versus 74.4% of patients in the SL group (p < 0.001). The reoperation rate was 18.9% in the SL group and 1.9% in the CSM group (p < 0.001). After propensity score-matched logistic regression, odds ratio (OR) for positive final margin status was 6.2 (95% confidence interval [CI] 2.85-13.46; p < 0.001) without CSM, while OR for reintervention was 5.46 (95% CI 2.21-13.46; p < 0.001). CSM significantly reduced positive margins and reexcisions for Luminal A, Luminal B, and triple-negative breast cancers (p < 0.001, p < 0.001, and p = 0.0137, respectively). SL had higher global costs compared with CSM: €193,630.6 versus €177,830 for 100 treated patients (p = 0.009).

CONCLUSIONS: CSM reduces reexcisions, mainly in luminal breast cancers, without increasing costs.