Patterns of relapse in older women diagnosed with estrogen receptor (ER)–positive early-stage breast cancer (BC) treated with lumpectomy without adjuvant endocrine therapy (ET)

Purpose Randomized trials comparing endocrine therapy (ET) with no ET show reduced overall relapse rates with adjuvant ET for patients with early-stage estrogen receptor (ER)–positive breast cancer (BC). Of note, these studies include few patients over the age of 65 years. Currently, with ET routinely prescribed, there is limited opportunity to study the patterns of relapse without ET. The objective of our study is to evaluate the rates of local-regional and distant relapse in older BC women who postoperatively did not receive ET.