Local control in ductal carcinoma in situ treated by excision alone: incremental benefit of larger margins

BACKGROUND: Margin width has been shown previously to be the most important predictor of local treatment failure after breast conservation for ductal carcinoma in situ (DCIS). METHODS: Five variables thought to be associated with local recurrence were evaluated by univariate and multivariate analysis in 455 nonrandomized patients with DCIS treated with excision alone. RESULTS: Multivariate analysis showed that margin width, age, nuclear grade, and tumor size all were independent predictors of local recurrence, with margin width as the single most important predictor. After adjusting for all other predictors the likelihood of local recurrence for patients with margins less than 10 mm was 5.39 times as much as that for patients with margins of 10 mm or more (95% confidence interval, 2.68-10.64). CONCLUSIONS: Margin width, the distance between DCIS and the closest inked margin, was the single most important predictor of local recurrence. As margin width increases, the risk for local recurrence decreases.