Abstract PO1-22-10: Long term outcomes of breast cancer patients with local recurrence after mastectomy undergoing immediate breast reconstruction: A retrospective multi-institutional study of 4153 cases

Abstract Background: The number of breast cancer patients in Japan undergoing immediate breast reconstruction (IBR) has increased and the postoperative follow-up period has been extended. This study was conducted to clarify the clinical aspects of and factors associated with local recurrence (LR) after IBR. Methods: This was a multicenter study which included 4153 early breast cancer patients who underwent IBR. Clinicopathological characteristics were examined and factors potentially contributing to LR were analyzed. Risk factors for LR were examined separately for non-invasive and invasive breast cancers. Results: The median follow-up period was 75 months. The 7-year LR rates were 2.1% and 4.3% for non-invasive and invasive cancers, respectively (p 0.001). The proportions of LR detected by palpation, subjective symptoms, and ultrasonography were 40.0%, 27.3%, and 25.9%, respectively. Overall, 75.7% of LR were solitary, and 92.7% of these cases had no further recurrences during the observational period. Multivariate analysis of LR for invasive cancer showed that skin-sparing mastectomy (SSM) or nipple-sparing mastectomy (NSM), the presence of lymphovascular invasion, cancer at the surgical margin, and not receiving radiation therapy were factors related to LR. The 7-year overall survival rates of the patients with LR and non-LR of invasive cancers were 92.5% and 97.3%, respectively, (p=0.002). Conclusions: The rate of LR after IBR was acceptably low and IBR can thus be performed safely for early breast cancer patients. Invasive cancer, SSM/NSM, lymphovascular invasion, and/or cancer at the surgical margin should prompt awareness of the possibility of LR. Citation Format: Akiko Ogiya, Naomi Nagura, Ayaka Shimo, Hiroko Nogi, Kazutaka Narui, Hirohito Seki, Hiroki Mori, Shinsuke Sasada, Makoto Ishitobi, Naoto Kondo, Chikako Yamauchi, Kohei Akazawa, Tadahiko Shien. Long term outcomes of breast cancer patients with local recurrence after mastectomy undergoing immediate breast reconstruction: A retrospective multi-institutional study of 4153 cases 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 PO1-22-10.