LAUSR

Simple Summary To date, breast conserving therapy has equivalent local control to mastectomy alone. However, it is not clear whether this finding is equally applied to young women because of the lack of large scale prospective randomized studies. In this study, we compared the local control between breast conserving therapy and mastectomy alone for young women with breast cancer. We found that young women who underwent breast conserving therapy had an approximately 2.5-fold increased risk of local recurrence compared with those receiving mastectomy alone. The prognosis of young women who had local recurrence after breast conserving therapy were poor despite the aggressive salvage treatments. Therefore, the development of more effective novel systemic treatments is required to improve treatment outcomes in young women with breast cancer receiving breast conserving therapy. Abstract We compared the cumulative incidence of local recurrence in young patients (≤40 years) with breast cancer between breast conserving therapy (BCT) and mastectomy alone. Among 428 women with early-stage breast cancer who were treated between 2001 and 2012, 311 underwent BCT and 117 underwent mastectomy alone. Adjuvant systemic treatments were administered to 409 patients (95.6%). We compared the cumulative incidence of LR and survival rates between two groups. During a median follow-up period of 91 months, the 10-year cumulative incidence of LR was 9.3% (median interval of 36.5 months from surgery). Patients treated with BCT tended to have a higher risk for local recurrence (11.1% for BCT vs. 4.1% for mastectomy alone, p = 0.078). All patients with isolated LR after BCT (n = 23) underwent salvage mastectomy followed by systemic treatments. The 5-year distant metastasis-free survival and overall survival of patients with isolated LR after BCT were 44.2% and 82.2%, respectively. The BCT group exhibited an approximately 2.5-fold higher risk of LR than mastectomy alone group. Patients with isolated LR after BCT showed poor prognosis despite undergoing aggressive salvage treatments. The development of novel treatments should be investigated to reduce LR for improving prognosis and preserving cosmetic outcomes in young women.