Abstract P2-14-03: Learning curve for Robotic assisted nipple sparing mastectomy: a single institution experience
Authors: Kim Yeon JIn , Chung Soo Yeon , Chae Byung Joo , Yu Jonghan , Lee Jeong Eon , Ryu Jai Min 
Published: March 2023

Abstract
Backgrounds/Aims: Nipple sparing mastectomy (NSM) is popularly performed as this surgical technique is oncological safety and better cosmetic outcomes. Robot assisted NSM (RANSM) is emerging because of its exceptional advantages: hidden incisions, high resolution, wider visualization and ergonomically moving. Although several studies reported that RANSM has shown a short learning curve, there were few reports about learning curve of this cutting-edge surgical technique. In this study, we reported the learning curve and feasibility of RANSM.
Methods: A retrospective and prospective study was conducted for women who underwent RANSM with immediate breast reconstruction at Samsung Medical Center from July 2019 to April 2022. All RANSM were performed by a single surgeon. We divided the total cases in half and set up two phases; an early phase (case 1st to 23th) and a late phase (case 24th to 46th). The total operation time, mastectomy time, docking time, pre-console time and console time was defined as the interval between the creation of the skin incision and the end of the reconstructive surgery, the interval between the time of skin incision and the time of the specimen out of the operation field, the interval between the preparation for docking and the end of docking, the interval between the creation of the skin incision and the end of robot docking, and the time spent by a surgeon to operate the console for mastectomy. To evaluate the impact of case experience accumulation on the operation time of RANSM, the cumulative sum (CUSUM) method was used to analyze the learning curve. Clinicopathologic characteristics, perioperative complications, and operation time were collected.
Results: Overall, 42 women underwent 46 RANSM procedures conducted. The median patient age was 44.5 years old (26-59 years) and the median breast weight was 338.5 gram (101.4-817 gram). BRCA 1 mutation carriers were 2 patients and BRCA 2 mutation carriers were 3 patients. 5 patients with BRCA 1/2 mutation carriers underwent contralateral risk-reducing RANSM. Clinicopathologic characteristics of patients between the early phase and late phase were summarized in Table 1. There were no significant differences in almost clinicopathologic characteristics. Median time of total operation, mastectomy, docking time, pre-console time, and console time was 344.0 minutes (254.0-480.0 minutes), 238.5 minutes (166-394 minutes), 6.5 minutes (1-25 minutes), 61.5 minutes (29-180 minutes), and 64.5 minutes (33-134 minutes), respectively. Comparing the early phase and the late phase, median total operation time was 357 minutes (273-480 minutes) and 321 minutes (254-459 minutes), (p = 0.067); median mastectomy time was 245 minutes (204-394 minutes) and 229 minutes (166-376 minutes), (p = 0.070); docking time 7.0 minutes (3-25 minutes) and 5.0 minutes (1-20 minutes),(p = 0.093); pre-console time was 70.0 minutes (49-162 minutes) and 54.0 minutes (29-180 minutes),(p = 0.028); console time was 71.0 minutes (40-134 minutes) and 60.0 minutes (33-105 minutes), (p = 0.095). In the learning curve analysis, it took the 21th procedure in RANSM to decrease the breast operation time. Clavien-Dindo grade III postoperative complication was two cases (8.6%, one case was infection and one case was nipple ischemia) in only early phase and none in the late phase. Clavien-Dindo grade II postoperative complication was absent in all phases. Clavien-Dindo grade I postoperative complications were seven cases (30.4%, all cases were nipple crust) in the early phase and one case (4.3%, one case was nipple crust) in the late phase. Nipple ischemia was found in two cases (8.6%) but only one case required nipple excision given in the early phase.
Conclusions: It has shown that the breast operation time improved from the 21th procedure of RANSM. RANSM is technically feasible and acceptable with a short learning curve.
TABLE 1. Basic characteristics of patients between the early phase and late phase
Citation Format: Yeon JIn Kim, Soo Yeon Chung, Byung Joo Chae, Jonghan Yu, Jeong Eon Lee, Jai Min Ryu. Learning curve for Robotic assisted nipple sparing mastectomy: a single institution experience [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 P2-14-03.