Examination of the use of Exemestane in patients with metastatic breast cancer

Abstract

Endocrine therapy is the preferred systemic treatment for metastatic breast cancer to prolong disease control. Aromatase inhibitors (AIs) are becoming the first choice for postmenopausal patients with metastatic breast cancer. AIs are divided into non-steroidal and steroidal agents. We retrospectively analyzed 81 patients with metastatic breast cancer who were administered Exemestane (EXE). The response rate (RR) and clinical benefit rate (CBR) were evaluated. No significant differences were observed between the first-line treatment group and the second- and third-line treatment groups with respect to the CBR. With respect to the CBR, patients with metastases only of the bone and soft tissue had superior results than those with visceral metastasis. There were no significant differences in the RR and CBR of EXE because of differences in prior treatments. On the other hand, no clinical response was achieved in any patients for whom Anastrozole (ANA) was used following EXE. With regard to the switch from EXE to tamoxifen and to medroxyprogesterone acetate, a CB response was not achieved in those receiving EXE, but it was achieved in the others. EXE following ANA had moderate efficacy, with a CBR of 39%. Moreover, a clinical response was achieved in 3 out of 10 patients in whom no response had been achieved with ANA. EXE seems to be a useful alternative treatment when the first-line treatment has not been effective. If the use of both agents, ANA and EXE, is planned, it might be desirable to initiate treatment with ANA and then switch to EXE.