Surgical margin reporting in breast conserving surgery: Does compliance with guidelines affect re-excision and mastectomy rates?

PURPOSE: Margin status is important in guiding decisions to re-excise following breast-conserving surgery (BCS) for breast cancer. The College of American Pathologists (CAP) developed guidelines to standardize pathology reporting; however, compliance with margin documentation guidelines has been shown to vary. The aim of this retrospective study was to determine whether compliance with CAP guidelines affects re-excision and mastectomy rates. METHODS: We identified 1423 patients diagnosed with breast cancer between 1998 and 2006 who underwent BCS with negative margins. CAP compliance was categorized as maximal, minimal, or non-compliant. Statistical analyses were performed comparing the frequency of re-excision and mastectomy after initial BCS according to CAP margin reporting guideline compliance. Data were adjusted for provider facility by including a clustering variable within the regression model. RESULTS: Patients with non-compliant margin reporting were 1.7 times more likely to undergo re-excision and/or mastectomy than those with maximally compliant reporting. Level of compliance was most strongly associated with the frequency of mastectomy; non-compliant margin reporting was associated with a 2.5-fold increase in mastectomy rates compared to maximally compliant reporting. The results did not substantially change when the analyses accounted for clustering at the provider facility level. CONCLUSIONS: Our findings suggest that compliance with CAP guidelines in pathology reporting may be associated with variation in re-excision and mastectomy rates following BCS.