Abstract P2-11-03: How to make decisions in ductal carcinoma in situ? The first study of clinical applicability of the MSKCC ductal carcinoma in situ nomogram in the prediction of local recurrence risk after breast conserving surgery in a Brazilian cohort

Abstract

Abstract Introduction: Radiation therapy (RT) plays an important role in the management of patients with ductal carcinoma in situ (DCIS) of the breast, treated by breast conserving surgery (BCS). RT reduces significantly the risk of local recurrences (LR). Efforts are being, currently, to de-escalate RT in this scenario with individualized decision-makings. Several biomarkers and clinical tools were developed to predict the probability of LR and aid a tailored clinical decision. The aim of this study is to assess the potential of the MSKCC DCIS Nomogram, which combines clinical, pathologic, and treatment features to forecast LR after BCS for DCIS patients and assist physicians to recommend RT. Methods: Were enrolled into the study women with DCIS undergoing BCS, with clear surgical margins, and external RT from 1993 to 2018 at a specialized breast cancer service in São Paulo, Brazil. The data were collected from medical records. The MSKCC DCIS Nomogram was applied to the study population. Receiver operating characteristic curve were drawn and the area under the curve (AUC) of 10-year risk of LR evaluation was calculated. Results: 110 women were eligible. Eight patients had LR (7,3%), being 5 invasives (62,5%) and 3 in situ (37,5%). The follow-up mean time was 4.8 years. Time to recurrence was 9.6 years with a 10 years risk of LR of 10,3%. The MSKCC DCIS Nomogram 10-year risk estimates showed satisfactory correlation as regard to LR with the AUC of 0.61. The nomogram is warranted for the 10-year risk LR prediction, and it may reinforce RT indication. Conclusions: The MSKCC DCIS Nomogram may identify patients with DCIS treated by BCS with high probability of LR, and therefore is a useful treatment decision aid for patients with DCIS and may assist the RT recommendation. Citation Format: Larissa Marques, Heloísa Carvalho, Filomena Carvalho, Luciana Rodrigues, Fernando Aguiar, Alfredo Barros. How to make decisions in ductal carcinoma in situ? The first study of clinical applicability of the MSKCC ductal carcinoma in situ nomogram in the prediction of local recurrence risk after breast conserving surgery in a Brazilian cohort [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P2-11-03.