Published in:
01-01-2021 | Mastectomy | Breast Oncology
Adoption of SSO-ASTRO Margin Guidelines for Ductal Carcinoma in Situ: What Is the Impact on Use of Additional Surgery?
Published in: Annals of Surgical Oncology | Issue 1/2021
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Background
Historically, more than one-third of patients with ductal carcinoma in situ (DCIS) treated with breast-conserving surgery (BCS) underwent additional surgery. The SSO-ASTRO guidelines advise 2 mm margins for patients with DCIS having BCS and whole-breast radiation (WBRT). Here we examine guideline impact on additional surgery and factors associated with re-excision.
Patients and Methods
Patients treated with BCS for pure DCIS from August 2015 to January 2018 were identified. Guidelines were adopted on September 1, 2016, and all patients had separately submitted cavity-shave margins. Clinicopathologic characteristics, margin status, and rates of additional surgery were examined.
Results
Among 650 patients with DCIS who attempted BCS, 50 (8%) converted to mastectomy. Of 600 who had BCS as final surgery, 336 (56%) received WBRT and comprised our study group. One hundred twenty-eight (38%) were treated pre-guideline and 208 (62%) were treated post-guideline. Characteristics and margin status were similar between groups. The re-excision rate was 38% pre-guideline adoption and 29% post-guideline adoption (p = 0.09), with 91% having only one re-excision. Re-excision for ≥ 2 mm margins was uncommon (6% pre-guideline vs. 5% post-guideline). On multivariate analysis, younger age (OR 0.97, 95% CI 0.94–0.99, p = 0.02) and larger DCIS size (OR 1.43, 95% CI 1.2–1.8, p < 0.001) were predictive of re-excision; guideline era was not. Younger age (OR 0.93, 95% CI 0.9–0.97, p < 0.001) and larger size (OR 1.64, 95% CI 1.3–2.1, p < 0.001) were predictive of conversion to mastectomy, but residual tumor burden was low.
Conclusions
The SSO-ASTRO guidelines did not significantly change re-excision rates for DCIS in our practice, likely since re-excision for margins ≥ 2 mm was uncommon even prior to guideline adoption, dissimilar to historically observed variations in surgeon practices. Younger age and larger DCIS size were associated with additional surgery.