Abstract GS5-01: Appropriate margins for breast conserving surgery in patients with early stage breast cancer: A meta-analysis

Background: Significant controversy exists regarding the appropriate minimum tumor-free margin width for patients undergoing breast-conserving therapy. The SSO-ASTRO guidelines recommend 'no ink on tumor' based upon a meta-analysis of 33 studies, but this had significant limitations. In order to address these concerns, a meta-analysis of all available data (using 31 of the initial studies) was performed but employing stricter criteria for acceptability and quality of evaluable studies. Methods: Study eligibility criteria were: (1) minimum follow-up of 50 months; (2) explicit pathologic criteria for defining margins; and (3) consistent endpoints associated with local recurrence. The compiled studies were analyzed using generalized linear mixed models for the outcome of local recurrence, with random effects for study and fixed effects for various patient and study characteristics. Results: The analysis incorporated 38 studies, which included 55,302 patients treated from 1968-2010. Two of the previous studies were excluded (one because of short follow-up, and the second because it was updated) with seven new studies added from the previous meta-analysis including an update of a previously included analysis. Median follow-up was 7.2 years. The median age of the cohort was 55 years, 74% of patients had T1 tumors, and 72% were node negative. The crude rate of local recurrence for patients with positive margins was 10.3%, compared to 3.8% for those with negative margins defined as no tumor on ink or wider (p0- Conclusions: The current meta-analysis indicates that having margin widths 2 mm or greater is associated with a lower risk of ipsilateral breast failure than narrower but uninvolved margins. It therefore fails to confirm that 'no-tumor on ink' is optimal. Further analyses are needed to clarify this issue, particularly to identify the critical minimum tumor-free margin for different patient subgroups. Citation Format: Shah C, Verma V, Sayles H, Recht A, Vicini F. Appropriate margins for breast conserving surgery in patients with early stage breast cancer: A meta-analysis [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 GS5-01.