This study aimed at evaluating following:~Validity Assessment:~Primary End Point: To evaluate 5-year diseae free survival rate after Letrozole treatment according to the estrogen receptor expression in postmenopausal women~Secondary End Point: To evaluate overall survival rate(OS) and Time to distance recurrence(TTDR) after Hormonal therapy in postmenopausal women with hormone receptor positive breast cancer~Safety Assessment: To evaluate all adverse events including serious adverse events after Letrozole treatment.
The purpose of this study is to assess clinical outcomes after Letrozole treatment according to the estrogen receptor expression in postmenopausal women with hormone receptor positive breast cancer.