Abstract PO5-03-02: Ductal carcinoma in situ: An excess regard of the axilla?

Abstract

Abstract Abstract: Ductal Carcinoma in Situ (DCIS) is a malignant proliferation of the epithelial inside the breast duct, which does not invade the myoepithelial layer and, therefore, does not have the capacity to generate metastases. [1]. However, an upstaging after surgery is possible, since there may be a concomitant invasive lesion that was not diagnosed in the pathological examination from biopsy, being discovered only after the surgical procedure [1]. In the pre-screening mammography era, DCIS was diagnosed. more commonly in symptomatic women presenting with a palpable nodule, papillary flow, or through an incidental finding on a breast biopsy [2], accounting for 1-2% of cancer cases. [3]. After the advent of mammographic screening, the incidence has considerably increased among asymptomatic women with mammographic changes such as calcifications. [4]. Nowadays the diagnosis of DCIS corresponds to 20-25% of biopsies secondary to screening mammographic changes. [1]. As we do know that the chance of axillary metastasis is potentially null, old series where axillary dissection (AD) was performed ipsilareral to the index tumor, axillary involvement was observed in less than 1% of cases [9]. Objectives: Our objective in this study was to describe in a single breast cancer reference center the surgical treatment of patients diagnosed with DCIS (mastectomy or breast conservative surgery – BCS). Methods: A retrospective analysis was made using the Pérola Byington Hospital’s database, from January 2011 to December 2019. During this period, 11,373 cases of breast cancer were treated int the institution and 812 (7.4%) were DCIS. Data was available and we could analyze 494 patients who underwent vacuum-guided biopsy guided by mammography or ultrasound and were diagnosed with DCIS and underwent surgical treatment at the Hospital. We grouped the patients into 3 age groups: under 40, 40-49, and 50 and over. In all groups, we had patients who underwent SNB using the patent blue technique or AD and were evaluated using the H&E method. It is not part of the Institutional protocol to perform IHC in axillary lymph nodes. We had also evaluated the type of surgery (BCS or mastectomy) in each age group. Results: DCIS was diagnosed through mammographic alterations in 62% of all cases and nuclear grade 2 was the most common, with 47%, followed by grade 3 and 1, 46% and 4%, respectively. In 2% of cases the data was missing. Comedoconecrosis was present in 78% of our specimens. BCS was the most frequently surgery performed (73% of cases), with the axillary approach being performed in 35% of these patients (32% for SNB and 3% for AD). While 27% of patients underwent radical surgery and in this group 92% were submitted to axillary approach (70% SNB and 22% AD). In the group of patients younger than 40 years, 74% of patients (17 out of 23 in total) underwent an axillary approach regardless of the type of surgery. When evaluating the predetermined age groups, we saw that most of our patients were 50 years or more (69%), followed by patients between 40-49 years (26%) and 5% in patients under 40 years. In 3% of cases (16 in 494) we reclassified the lesion as invasive carcinoma. None of them had a lymph node involved by malignant cells after surgery and that’s include the cases reclassified as invasive carcinoma. Conclusion: The results obtained in this analysis showing no axillary involvement will make us rethink the indications for the concomitant surgical approach of the breast and the axilla in cases with a diagnosis of DCIS as a way to reduce the axillary surgical overtreatment. It was not our goal to compare the costs and complications of each method of diagnosis and the prognostic factors after the treatment of DCIS. Citation Format: Andressa Amorim, Andre Mattar, Marcellus Ramos, Reginaldo Coelho Lopes, Luciana Damous, Luiz Henrique Gebrim. Ductal carcinoma in situ: An excess regard of the axilla? [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO5-03-02.