Abstract P2-14-17: Long-term oncologic safety of nipple-sparing mastectomy with immediate reconstruction

Background Nipple-sparing mastectomy (NSM) is an alternative procedure to skin-sparing mastectomy (SSM) for selected patients who undergo immediate reconstruction. However, the evidence of long-term oncologic safety of NSM has not been established. In this study, we aimed to compare the prognosis of breast cancer patients who underwent NSM to those who underwent SSM with immediate reconstruction. Methods The clinicopathological factors including recurrence site, pathologic stage, nipple-tumor distance, histological type, lymphovascular invasion, margin status, ER, PgR and HER2 status of stage 0–III primary breast cancer patients who underwent NSM or SSM with immediate primary reconstruction with tissue expander from our breast center database was retrospectively assessed. Patients with a nipple tumor distance of Results The median follow-up period was 71 months (range: 10 - 131 months) for the NSM group and 79 months (range: 9 - 140 months) for the SSM group. There were no significant difference of clinicopathological factors between the NSM group and the SSM group, except of the larger diameter of tumor in the SSM group. NSM was performed for 60 patients (32%) with stage 0, 71 patients (37%) with stage I, and 59 patients (31%) with stage II/III. SSM was performed for 185 patients (26%) with stage 0, 268 patients (37%) with stage I, and 276 patients (37%) with stage II/III. Local recurrence was found in 11 (5.8%) patients in the NSM group and in 44 (6.0%) patients in the SSM group. In the NSM group, only one (0.5%) patient had local recurrence in the nipple areola complex. In terms of DFS and overall survival (OS) rate, there was no difference between the NSM group and the SSM group (DFS; 89.5% vs 89.2%, HR, 1.044; p = 0.8992; 95% CI, 0.5116–1.9519, and OS; 98.4% vs 96.4%, HR, 0.963; p = 0.9116; 95% CI, 0.473–1.793). According to breast cancer subtype, in the NSM group, all of the 11 patients (100%) who developed local recurrence in the NSM group was hormone receptor (HR)-positive/HER2-negative breast cancer. 29 of the 44 patients (65.9%) who developed local recurrence in the SSM group was HR-positive/HER2-negative, 6 patients (13.6%) was HR-negative/HER2-positive, and 7 patients (15.9%) was triple-negative breast cancer. Among patients who had received neoadjuvant chemotherapy, the NSM group (3 of 14 patients, 21.4%) had a trend for higher local recurrence rate than the SSM group 7 of 116 patients (6.0%) (p = 0.0813). However, no local recurrence in the nipple areola complex was observed for the NSM group. In addition, there was no difference of OS between the NSM group (92.9%) and the SSM group (90.5%) (HR, 0.903; p = 0.9943; 95% CI, 0.049-4.739). Conclusions Our results suggested that NSM with immediate reconstruction might be safe as well as SSM for breast cancer with the nipple–tumor distance of >1 cm with respect to their prognosis and local control regardless of breast cancer subtype or invasiveness. Further studies with a large sample size to assess the risk of local recurrence for NSM after neoadjuvant chemotherapy. Citation Format: Yamashita Y, Hayashi N, Nagura N, Kajiura Y, Yoshida A, Takei J, Suzuki K, Tsunoda H, Yamauchi H. Long-term oncologic safety of nipple-sparing mastectomy with immediate reconstruction [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-14-17.