SAN ANTONIO (EGMN) - Analysis of the biomarker Ki67 from a tumor biopsy obtained just 2-4 weeks into neoadjuvant endocrine therapy may provide valuable insight into therapeutic response among postmenopausal women with estrogen receptor-positive, HER2-negative breast cancer.In two trials, patients with a tumor Ki67 cut point value greater than 10% after undergoing a few weeks of endocrine therapy were found to have significantly poorer outcomes than did those whose biomarker expression was low, Dr....