Retrospective study of patient-level evaluation of optimal margin width for lumpectomy in ductal carcinoma in situ

Re-excision for close margins in patient undergoing breast-conserving surgery (BCS) for ductal carcinoma in situ (DCIS) aims to reduce recurrence rates. The current recommended margin width of ≥ 2 mm is based on study-level data. Analysis of patients in the multicenter National Cancer Database Special Study evaluated patient-level optimal margin width. The study included 11,156 women undergoing BCS with or without radiotherapy for DCIS between 2008 and 2015. Median age at diagnosis was 61 years and median follow-up was 66.6 months. Final margin width was categorized as positive (tumor on ink), 0.01-0.9 mm, 1.0-1.9 mm, or ≥ 2.0 mm. A total of 445 (4%) women experienced a recurrence during follow-up. In multivariable adjusted analysis, there was significant difference in recurrence risk between the negative margin groups both in patients who had either BCS with radiation or BCS alone. In subgroup analyses by age, race, hormone status, grade, size, endocrine therapy, and radiation treatment, only the age <50 years subgroup showed a significant difference in recurrence risk between narrow (0.01-1.9 mm) and wide (≥ 2.0 mm) margins. The authors conclude that negative margins < 2 mm were not associated with a higher local recurrence risk compared with margins ≥ 2 mm except in patients younger than 50 years at diagnosis (graphical abstract).