Efficacy of letrozole for advanced breast cancer in postmenopausal patients.

Objective: To evaluate the clinical benefit and tolerability of letrozole after tamoxifen failure in locally advanced, recurrent or metastatic breast cancer in postmenopausal patients.

Design: A phase II non-randomized trial.

Place And Duration Of Study: Oncology Department, Combined Military Hospital, Rawalpindi, from March 1999 to February 2001 over a period of 2 years.

Patients And Methods: One hundred and seventeen patients with tamoxifen failure were treated with letrozole 2.5 mg once daily, through oral route. All the accrued patients were either estrogen/progesterone receptor positive or unknown with KPS of more than 50%. Patients who had prior hormone therapy other than tamoxifen, or more than one chemotherapy for recurrent or advanced disease were not enrolled in the study. Time to progression (TTP) was the primary objective, whereas objective response (OR), duration and rate of clinical benefit (complete response + partial response + stable disease >6 months), tolerability and effects on quality of life were the secondary end points.

Results: The clinical benefit was 47.0% with an objective response of 28.2%. The objective response and median time to progression in soft tissue disease was better than in the visceral and bone disease. The median time to progression for patients having positive estrogen receptor / progesterone receptors (ER / PR) was 9.5 months which is slightly higher than in patients having unknown ER / PR status. The treatment with letrozole was well-tolerated with side effects observed in only 14 patients.

Conclusion: Letrozole is an effective hormone therapy after tamoxifen failure since it has significant clinical benefit and objective response. It can be safely used as second line hormone therapy in postmenopausal patients with locally advanced or metastatic breast cancer.