Tang M, O'Connell RL, Amant F, et al. - Among patients with estrogen receptor (ER) and/or progesterone receptor (PR) positive low-grade ovarian cancer (LGOC) and serous borderline ovarian tumor (SBOT), a prospective inquiry was undertaken to determine the clinical benefit rates (CBR) of anastrozole, an aromatase inhibitor. Until progression or unacceptable toxicity, anastrozole 1 mg was administered daily to post-menopausal women having ER-positive and/or PR-positive recurrent/metastatic LGOCs and SBOTs and evaluable disease by RECIST v1.1 or GCIG CA125 criteria. This study included 36 patients. The primary endpoint was a clinical benefit at 3 months, which was seen in 23 patients and was found to be similar at 6 months. The median duration of clinical benefit and median PFS were 9.5 months and 11.1 months, respectively. Findings revealed the acceptable toxicity as well as the ability of anastrozole in providing a CBR of 61% of patients with recurrent ER-positive and/or PR-positive LGOC or SBOT for at least 6 months.