Background: The oncologic goal of margin-negative breast conservation requires adequate localization of tumor. Intraoperative ultrasound remains most feasible but under-utilized method to localize the tumor and assess margins.
Methods: A prospectively maintained breast cancer database over a decade was queried for margin status in breast cancer patients undergoing breast conservation. Techniques of tumor localization, margin re-excision and closest margins were analyzed. Rate of conversion to mastectomy was determined.
Results: Of the 945 breast cancer patients treated at a university-based Breast Center of Excellence between January 1, 2009 and December 31, 2018, 149(15.8%) had ductal carcinoma in situ; 712(75.3%) had invasive ductal carcinoma, and 63(6.7%) had invasive lobular carcinoma. Clinical stage distribution was: T1 = 372(39.4%); T2 = 257(27.2%); T3 = 87(9.2%). Five hundred and eighty three (61.7%) patients underwent breast conservation. The median (25th -75th centile) closest margin was 6(2.5, 10.0) mm. Thirty five (6.0%) patients underwent margin re-excision, of which 9(25%) were converted to mastectomy. Tumor localization was achieved with ultrasound in 521(89.4%) patients and with wire localization in 62(10.6%) patients. The median (25th-75th centile) closest margin with wire localization was 5.0(2.0, 8.5) mm versus 5.0 (2.0, 8.0) mm with ultrasound guidance [p = 0.6635]. The re-excision rate with wire localization was 14.5% versus 4.9% with ultrasound guidance [p = 0.0073]. The unadjusted Odds Ratio (95% CI) for margin revision in wire localized group compared with ultrasound was 3.2 (7.14, 1.42) [p = 0.0045]; multivariate adjusted OR (95%) was 4(9.09, 1.7) [p = 0.0013].
Conclusions: Ultrasound guidance for localization of breast cancer remains the most effective option for margin negative breast conservation.
Keywords: Breast conservation; Intraoperative ultrasound; Tumor localization; Tumor margin.
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