Clinical Outcomes Following Letrozole Treatment according to Estrogen Receptor Expression in Postmenopausal Women: LETTER Study (KBCSG-006)Clinical Outcomes Following Letrozole Treatment according to Estrogen Receptor Expression in Postmenopausal Women: LETTER Study (KBCSG-006)
- Other Titles
- Clinical Outcomes Following Letrozole Treatment according to Estrogen Receptor Expression in Postmenopausal Women: LETTER Study (KBCSG-006)
- Authors
- Sung Gwe Ahn; 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
- Issue Date
- Apr-2021
- Publisher
- 한국유방암학회
- Keywords
- Breast neoplasms; Letrozole; Postmenopause; Receptors; estrogen
- Citation
- Journal of Breast Cancer, v.24, no.2, pp.164 - 174
- Journal Title
- Journal of Breast Cancer
- Volume
- 24
- Number
- 2
- Start Page
- 164
- End Page
- 174
- URI
- https://scholarworks.bwise.kr/gachon/handle/2020.sw.gachon/81006
- DOI
- 10.4048/jbc.2021.24.e17
- ISSN
- 1738-6756
- 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.
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