Abstract P3-18-11: Meeting the challenge of successful one-stage lumpectomy for DCIS

Introduction: Positive lumpectomy margins are associated with an increased risk for ipsilateral tumor recurrence, and necessitate additional procedures to achieve acceptable margins. Re-excision rates are higher in patients with ductal carcinoma in situ (DCIS) versus those with invasive carcinoma. The purpose of this study was to investigate the clinicopathologic characteristics, surgical techniques, and other outcomes associated with re-excision over time following primary breast conserving surgery for DCIS. Methods: Our institutional Breast Cancer Database was queried for patients treated with lumpectomy as the primary procedure for pure DCIS from 2010-2021. Cases of microinvasive disease were excluded. The primary endpoint was the rate of re-excision following lumpectomy. Variables of interest included patient demographics and clinicopathologic characteristics. As a secondary analysis, adjusted odds ratios for the association of MarginProbe® with re-excisions were calculated using a multivariable logistic regression model controlling for age, tumor size, breast density and DCIS subtype. Individual comparisons of continuous variables were based on t-tests, group proportions compared with one-way ANOVA, and categorical variables compared using Chi Square tests. Results: Out of a total of 695 patients in our cohort, 221 (32%) had re-excisions. There was a statistically significant 2% decline per year in the number of re-excisions (p=0.005). Patients who underwent re-excision had larger size of DCIS (2.37 cm vs 1.37 cm, p Table 1.Clinicopathologic CharacteristicsVariableNo Re-excision (n=313)Re-Excision (n=100)P-ValueAge; mean (SD)61.48 (12.01)58.04 (13.39)0.016Age of Menopause; mean (SD)50.22 (5.18)48.13 (5.45)0.004Size of DCIS; mean (SD)1.37 (1.25)2.37 (2.00)0 and Citation Format: Joshua A Feinberg, Charles DiMaggio, Nakisa Pourkey, Jennifer Chun Kim, Jenny Goodgal, Amber Guth, Deborah Axelrod, Freya Schnabel. Meeting the challenge of successful one-stage lumpectomy for DCIS [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P3-18-11.