Background: HER2/neu is a potentially interesting variable that has been demonstrated to have a profound impact on the management of invasive breast carcinoma, and we performed this study to evaluate the differences between HER2-positive and HER2-negative ductal carcinoma in situ. The impetus for this study was our poor recruitment to the National Surgical Adjuvant Breast and Bowel Project Protocol B-43 trial that was designed to evaluate the potential role of trastuzumab in breast conservation therapy for patients with HER2-positive ductal carcinoma in situ.
Methods: All patients with ductal carcinoma in situ and an assessment for the HER2/neu receptor were identified. Patients with HER2-positive and HER2-negative ductal carcinoma in situ were compared to determine differences in demographic, hormone receptor status, nuclear grade, presence of necrosis, surgical procedure (lumpectomy or mastectomy), tumor size, and extent of margins. Quantitative variables were analyzed with t test, and nominal variables were assessed by chi square analysis.
Results: A total of 177 patients were identified with a mean age of 61.0 years. A total of 101 patients (57.1%) were treated with lumpectomy, and 76 had mastectomy (42.9%). Forty-four (24.9%) patients were positive, and 133 (75.1%) were negative for the HER2/neu receptor. HER2-positive tumors were larger (23.6 vs 13.8 mm, P=0.001) and more likely to undergo mastectomy (61.4% vs 36.8%, P=0.01).
Conclusion: Based on these results, an HER2-positive ductal carcinoma in situ is likely to be larger than an HER2-negative tumor, leading to more frequent use of mastectomy. This finding would explain our poor recruitment to the National Surgical Adjuvant Breast and Bowel Project Protocol B-43 trial.
Keywords: Carcinoma–ductal–breast; HER2/neu; mastectomy; radiation; trastuzumab.