Third-line hormonal treatment with exemestane in postmenopausal patients with advanced breast cancer progressing on letrozole or anastrozole. A phase II trial conducted by the Hellenic Group of Oncology (HELGO).

Aims And Background: The understanding of hormonal therapies in postmenopausal women with metastatic breast cancer has advanced greatly in the past several decades. With the introduction of orally active, potent and selective third-generation aromatase inhibitors (anastrozole, letrozole and exemestane), approaches to the treatment of hormone-sensitive advanced breast cancer are undergoing reevaluation. For treatment of advanced or metastatic disease that has progressed on tamoxifen, all three agents are active. The purpose of the study was to assess the antitumor efficacy and tolerance of exemestane administered as third-line hormonal therapy to postmenopausal women with metastatic breast cancer refractory to letrozole and anastrozole.

Study Design: Sixty postmenopausal women with stage IV hormone receptor-positive carcinoma of the breast were enrolled in the study. All patients had received two prior hormonal manipulations and had measurable or assessable disease. All adverse events were monitored.

Results: Objective tumor response was achieved in 12 (20%) patients (95% CI, 9.6-30.4). The overall clinical benefit was 38.3% (95% CI, 21.2-49.3), and the median duration of objective tumor response was 20 months (range, 9-26). The median time to death was 17.4 months (95% CI, 16.14-18.66).

Conclusions: Exemestane represents an active and well-tolerated treatment option in pretreated patients with advanced breast cancer who have received standard first- and second line hormonal therapies. By extending the sequence of hormonal therapy, disease progression and the need for chemotherapy may be significantly delayed.