Wapnir IL, et al. - Isolated locoregional recurrence (ILRR) predicts a high risk of developing breast cancer distant metastases and death. A report at 5 years of median follow-up among the participants of the Chemotherapy as Adjuvant for LOcally Recurrent breast cancer (CALOR) trial, which investigated the effectiveness of chemotherapy (CT) after local therapy for ILRR, demonstrated significant benefit of CT for estrogen receptor (ER)–negative ILRR. The final analysis of CALOR corroborated beneficial impact of CT in patients with resected ER-negative ILRR and did not support the use of CT for ER-positive ILRR.