• Christine Tunon-de-Lara, Marie Pierre Chauvet, Marie Christine Baranzelli, Marc Baron, Jean Piquenot, Guillaume Le-Bouédec, Fréderique Penault-Llorca, Jean-Rémi Garbay, Jérôme Blanchot, Joëlle Mollard, Véronique Maisongrosse, Simone Mathoulin-Pélissier, and Gaëtan MacGrogan.
• Department of Surgery, Institut Bergonié, Comprehensive Cancer Centre, Bordeaux, France. c.tunondeLara@bordeaux.unicancer.fr.
• Ann. Surg. Oncol. 2015 Nov 1; 22 (12): 3853-60.

BackgroundWhen invasive components are discovered at mastectomy for vacuum-assisted biopsy (VAB)-diagnosed ductal carcinoma in situ (DCIS), the only option available is axillary lymph node dissection (ALND). The primary aim of this prospective multicenter trial was to determine the benefit of performing upfront sentinel lymph node (SLN) biopsy for these patients. The secondary aim was to determine DCIS factors associated with microinvasion or invasion.MethodsThe SLN procedure was performed during mastectomy, and for positive SLN an ALND was performed during the same intervention. A tissue microarray containing DCIS lesions from the mastectomy specimens was subsequently performed.ResultsFrom May 2008 to December 2010, 228 patients were enrolled from 14 French cancer centers, including 192 eligible patients with pure DCIS on VAB and successful SLN procedures. ALND was avoided for 51 [67 %; 95 % confidence interval (CI), 56-77 %] of all the patients who had microinvasive DCIS or DCIS associated with invasive carcinoma at mastectomy and a negative SLN. Of the 192 patients, 76 (39 %) with VAB-diagnosed DCIS were upgraded after mastectomy to micro (n = 20) or invasive disease (n = 56). The rate of positive SLN for patients with DCIS on VAB was 14 %. High nuclear grade of DCIS was associated with greater risk of microinvasion and invasion, and HER2-amplified DCIS was associated with greater risk of invasion.ConclusionsUnderestimation of invasive components is high when DCIS is diagnosed by VAB in patients undergoing mastectomy. Upfront SLN for patients with VAB-diagnosed extensive DCIS avoids unnecessary ALND for two-thirds of patients with micro or invasive disease on mastectomy.

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