, Volume 14, Issue 5, pp 1618-1628
Date: 14 Feb 2007

Factors Affecting Successful Breast Conservation for Ductal Carcinoma in Situ

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Abstract

Background

Successful breast-conserving therapy in DCIS is restricted by high rates of residual disease resulting in the need for radiotherapy and/or re-excision. This study identifies patients with DCIS who are most at risk of compromised margins and of residual disease.

Methods

All patients undergoing breast-conserving surgery for DCIS over a 6-year period were included. Method of diagnosis, mammographic size, pathological size, DCIS-margin distance and residual disease on re-excision were analysed.

Results

One hundred and thirty-five patients underwent initial breast-conserving surgery for DCIS. The compromised margin rate was 72%, and the rate of residual disease on re-operation was 54%. On univariate analysis, underestimation of pathological size by mammography by >1 cm occurred in 40% of those with compromised margins undergoing a therapeutic operation compared to only 14% of those with clear margins (= 0.02). However, on multivariate analysis only pathological size (< 0.0001, OR = 1.0,95% CI 1.037–1.128) and lack of a preoperative diagnosis by core biopsy (< 0.0001, OR = 5.3,95% CI 1.859–15.08) were predictive of compromised margins. The presence of residual disease on re-excision was associated with increasing pathological size (< 0.0001, OR = 1.085,95% CI 1.038–1.134) and decreasing DCIS-margin distance (= 0.03, OR = 6.694,95% CI 1.84–37.855). Twenty-nine percent (n = 13/45) of lesions ≤3 cm compared to 84% (n = 27/32) of lesions >3 cm had residual disease on re-operation (< 0.0001). Residual disease was present in 62% (n = 34/55), 64% (n = 7/11) and 17% (n = 2/12) of patients with DCIS-margin distances ≤1, 1–2 and 2–5 mm, respectively.

Conclusion

Considerable underestimation of DCIS extent by mammography occurs in a high proportion of patients with compromised margins in breast conservation. Patients at particularly high risk of residual disease on re-excision are those with lesions >3 cm and those with DCIS-margin distances of ≤ 2mm.