Abstract OT2-12-01: Mastectomy with reconstruction including robot endoscopic surgery (MARRES): A prospective cohort study of the Korea robot-endoscopy minimal access breast surgery study group (KoREa-BSG)

Abstract Background: Robot nipple sparing mastectomy (RNSM) has emerged for breast cancer treatment and for risk reducing mastectomy in women who have high risk of pathogenic variants. Even though several studies have reported that RNSM is a feasible procedure, some argue that RNSM are only performed by several specialized surgeons and there is only limited data reporting about the oncologic outcome and patient reported outcome (PRO). Recently, the United States Food and Drug Administration and several surgeons have warned that robot breast surgery should be performed only by specialized surgeons and the benefits, risks, and alternatives of all available treatment options should be discussed with patients to make the most informed treatment decision. The Korea Robot-Endoscopy Minimal Access Breast Surgery Study Group (KoREa-BSG) has been established to evaluate, standardize, and developing education program this cutting-edge procedure. We designed a multicenter prospective cohort study of Mastectomy with Reconstruction including Robot Endoscopic Surgery (MARRES) to report surgical outcome, PRO, and oncologic outcome. Methods: The MARRES study is a multi-institution cohort study that prospectively collects data from patients undergoing mastectomy and reconstruction. Patients' inclusion criteria are as below; adult women over the age of 19, with breast cancer or high risk of breast cancer (patients with a BRCA1/2 mutation, TP53 mutation, and PALB2 mutation), who scheduled therapeutic or prophylactic mastectomy, and who want immediate reconstruction. Surgical outcomes, oncologic outcomes, cost-effectiveness, and PRO were collected. The primary endpoints were postoperative complication rates in postoperative 30 days and Clavien-Dindo grade of postoperative complications in postoperative 180 days. The secondary endpoints were recurrence free survival in postoperative 5 years, cancer incidence rate in postoperative 5 years for those who underwent risk reducing mastectomy, patient's satisfaction within preoperative 4 weeks and results within postoperative 6 months to 12 months, surgeon's satisfaction about the postoperative results in postoperative 6 months, and cost-effectiveness of the definitive surgery. Patient recruitment will be finished in April 2025 and the goal number of enrolled patients is 2,000. Discussion: This study will provide evidence of the surgical outcome, PRO, and oncologic outcome of RNSM and endoscopic NSM compared to conventional NSM. Trial registration: ClinicalTrials.gov Identifier NCT04585074. Registered April 8, 2020. Citation Format: Jeea Lee, Jai Min Ryu, Jee Yeon Lee, Beom Seok Ko, Saebyeol Lee, Joo Heung Kim, Hee Jun Choi, Hyuk-Jae Shin, Young Woo Chang, Hye Yoon Lee, Hong-Kyu Kim, Hyung Seok Park. Mastectomy with reconstruction including robot endoscopic surgery (MARRES): A prospective cohort study of the Korea robot-endoscopy minimal access breast surgery study group (KoREa-BSG) [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr OT2-12-01.