Among patients with ductal carcinoma in situ (DCIS) who underwent breast-conserving surgery, negative surgical margins narrower than 2 mm were not associated with a significantly higher risk of ipsilateral recurrence compared with margins of at least 2 mm—except among patients younger than age 50—according to findings from a large patient-level analysis reported by Nash et al in the Journal of Clinical Oncology.
Current consensus guidelines recommend a negative margin of at least 2 mm for patients with DCIS undergoing breast-conserving surgery with whole-breast radiotherapy; however, the investigators noted that this recommendation was based on study-level meta-analysis rather than patient-level data, and that the optimal negative margin width remains uncertain.
Study Details
Investigators conducted a retrospective observational cohort study using data from the 2017 Commission on Cancer Special Study on DCIS. The analysis included women aged 18 years and older diagnosed with biopsy-confirmed DCIS between 2008 and 2015 who underwent lumpectomy within 6 months of diagnosis. The final cohort was comprised of 11,156 patients from 1,231 Commission on Cancer sites.
The median age at diagnosis was 61 years, and median follow-up was 66.6 months. Overall, 72.2% of patients received breast-conserving surgery plus radiotherapy and 27.8% underwent surgery alone. Most tumors (81.5%) were hormone receptor–positive, 38.6% were grade 3, and 62.9% measured 2 cm or less. Final surgical margin width was categorized as positive (tumor on ink), 0.01 to 0.9 mm, 1.0 to 1.9 mm, or ≥ 2 mm. The primary outcome was ipsilateral recurrence of either DCIS or invasive breast cancer.
Key Results
During follow-up, 445 patients (4.2%) experienced an ipsilateral recurrence. Among the 8,059 patients who received radiotherapy, 5-year cumulative recurrence rates were 4.4% for positive margins, 2.3% for margins of 0.01 to 0.9 mm, 3.4% for margins of 1.0 to 1.9 mm, and 2.0% for margins of ≥ 2 mm. Neither negative margin category below 2 mm differed significantly from the ≥ 2-mm group.
Among the 3,097 patients who did not receive radiotherapy, corresponding 5-year recurrence rates were 8.4%, 7.5%, 3.6%, and 4.7%, respectively. After multivariable adjustment, positive margins were associated with increased recurrence risk compared with margins ≥ 2 mm both among patients receiving radiotherapy (hazard ratio [HR] = 2.06, 95% confidence interval [CI] = 1.52–2.79) and those not receiving radiotherapy (HR = 1.55, 95% CI = 1.07–2.24). In contrast, narrower negative margins were not associated with a significantly increased risk of recurrence compared with wider negative margins, regardless of radiotherapy use.
Exploratory subgroup analysis identified age as a potential exception. Among patients younger than 50, negative margins below 2 mm were associated with a higher recurrence risk compared with margins ≥ 2 mm (HR = 1.94, 95% CI = 1.26–2.99).
The investigators concluded: “In this multivariable analysis of 11,156 patients, 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.”
E. Shelley Hwang, MD, MPH, MBA, of the Department of Surgery, Duke University Medical Center, Durham, North Carolina, is the corresponding author for the Journal of Clinical Oncology article.
DISCLOSURE: The study was supported by NCDB-SS and Breast Cancer Research Foundation. For full disclosures of the study authors, visit ascopubs.org.
