Clinical Outcomes Following Letrozole Treatment according to Estrogen Receptor Expression in Postmenopausal Women: LETTER Study (KBCSG-006)
- Author:
Sung Gwe AHN
1
;
Seok Jin NAM
;
Sei Hyun AHN
;
Yongsik JUNG
;
Heung Kyu PARK
;
Soo Jung LEE
;
Sung Soo KANG
;
Wonshik HAN
;
Kyong Hwa PARK
;
Yong Lai PARK
;
Jihyoun LEE
;
Hyun Jo YOUN
;
Jun Hyun KIM
;
Youngbum YOO
;
Jeong-Yoon SONG
;
Byung Kyun KO
;
Geumhee GWAK
;
Min Sung CHUNG
;
Sung Yong KIM
;
Seo Heon CHO
;
Doyil KIM
;
Myung-Chul CHANG
;
Byung In MOON
;
Lee Su KIM
;
Sei Joong KIM
;
Min Ho PARK
;
Tae Hyun KIM
;
Jihyoung CHO
;
Cheol Wan LIM
;
Young Tae BAE
;
Gyungyub GONG
;
Young Kyung BAE
;
Ahwon LEE
;
Joon JEONG
Author Information
- Publication Type:Original Article
- From:Journal of Breast Cancer 2021;24(2):164-174
- CountryRepublic of Korea
- Language:English
-
Abstract:
Purpose:In this trial, we investigated the efficacy and safety of adjuvant letrozole for hormone receptor (HR)-positive breast cancer. Here, we report the clinical outcome in postmenopausal women with HR-positive breast cancer treated with adjuvant letrozole according to estrogen receptor (ER) expression levels.
Methods:In this multi-institutional, open-label, observational study, postmenopausal patients with HR-positive breast cancer received adjuvant letrozole (2.5 mg/daily) for 5 years unless they experienced disease progression or unacceptable toxicity or withdrew their consent. The patients were stratified into the following 3 groups according to ER expression levels using a modified Allred score (AS): low, intermediate, and high (AS 3–4, 5–6, and 7–8, respectively). ER expression was centrally reviewed. The primary objective was the 5-year disease-free survival (DFS) rate.
Results:Between April 25, 2010, and February 5, 2014, 440 patients were enrolled. With a median follow-up of 62.0 months, the 5-year DFS rate in all patients was 94.2% (95% confidence interval [CI], 91.8–96.6). The 5-year DFS and recurrence-free survival (RFS) rates did not differ according to ER expression; the 5-year DFS rates were 94.3% and 94.1%in the low-to-intermediate and high expression groups, respectively (p = 0.6), and the corresponding 5-year RFS rates were 95.7% and 95.4%, respectively (p = 0.7). Furthermore, 25 patients discontinued letrozole because of drug toxicity.
Conclusion:Treatment with adjuvant letrozole showed very favorable treatment outcomes and good tolerability among Korean postmenopausal women with ER-positive breast cancer, independent of ER expression.
