Abstract P3-08-07: Margins in breast conserving surgery after neoadjuvant therapy

Background:The margin consensus guideline for patients undergoing primary breast conserving surgery (BCS) and whole breast radiotherapy defines a negative margin as no tumor on ink and concludes that wider margins do not improve local recurrence (LR) rates. There are few studies examining BCS margin width after neoadjuvant chemotherapy (NAC).We sought to determine the impact of margin width on LR and survival rates after NAC and BCS. Methods: Institutional database were reviewed to identify patients with stage I-III breast cancer treated with NAC and BCS from 2002-2014. Patients with inflammatory breast cancer were excluded. Chart review was performed to collect detailed patient and treatment factors. Margins widths were collected as reported and grouped as: positive (ink on tumor), close (2mm), for the purposes of this analysis. Cox regression was used to determine the relationship between margin width and local recurrence, disease free survival (DFS) and overall survival (OS). Result: 395 patients underwent NAC followed by BCS during the study period. The result was same as below. results Patients, n (%)Age at diagnosis (yrs)51 [22;79]Initial tumor size (cm)3.0 [0.6;11.0]Clinical node status - negative207 (52.4%)- positive188 (47.6%)subtype - HR-/Her2-148 (37.5%)- HR-/Her2+48 (12.2%)- HR+/Her2-124 (31.4%)- HR+/Her2+72 (18.2%)- unclassified3 ( 0.8%)pCR* status - pCR97 (24.6%)- non pCR295 (74.7%)- unclassified3 ( 0.8%)Final margin state - no residual tumor in breast108 (27.3%)- positive8 ( 2.0%)- close (≤2)99 (25.1%)- negative (>2)180 (45.6%)*pCR was defined as no invasive or in situ disease in breast and no tumor in axillary node Median patient age was 51 yrs (range 22-79); median tumor size at presentation was 3.0 cm (range 0.6-11.0) and 188 (47.6%) patients (pts) presented with clinically node positive disease. Breast cancer subtypes included 148 (37.5%) pts with HR-/Her2-, 48 (12.2%) pts with HR-/Her2+, 124 (31.4%) pts with HR+/Her2- and 72 (18.2%) pts with HR+/Her2+, disease. Among all patients the pCR rate, defined as no invasive or in situ disease, in the breast was 27.3% (108/395) and the pCR rate in the breast and axillary nodes was 24.6% (97/395). Final margin status included 8 (2.0%) pts with positive margins, 99 (25.1%) with close 2mm) margins. Among the patients with “positive margins”; all were noted to be posterior or anterior and the surgeon noted that re-excision was not possible. At a median follow-up of 53.0 months the LR rate was 2.8% and DFS was 87.4%. On cox regression, HR positive subtype (p=0.048), pCR (p=0.035), and pathologic negative node (p2mm margin groups. Conclusion: In this cohort of patients treated with NAC followed by BCS, LR rates were very low and there was no difference in DFS between patients with margins < 2mm or > 2mm. Further studies are needed to confirm the effect of margin width in the NAC setting. Citation Format: Choi J, Golshan M, Hu J, Gagnon HC, Densantis S, Barry B, King T. Margins in breast conserving surgery after neoadjuvant therapy [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P3-08-07.