Adjuvant tamoxifen switched to exemestane treatment in postmenopausal women with estrogen receptor-positive early breast cancer: A pragmatic, multicenter, and prospective clinical trial in China

Binghe Xu; Huiping Li; Zefei Jiang; Lin Gu; Jinhai Tang; Hui Xie; Yueyin Pan; Yunjiang Liu; Shude Cui; Xiaojia Wang; Li Cai; Yiqiong Zhang; Huadong Zhao; Zhimin Shao

doi:10.21147/j.issn.1000-9604.2022.06.07

Adjuvant tamoxifen switched to exemestane treatment in postmenopausal women with estrogen receptor-positive early breast cancer: A pragmatic, multicenter, and prospective clinical trial in China

Chin J Cancer Res. 2022 Dec 30;34(6):592-600. doi: 10.21147/j.issn.1000-9604.2022.06.07.

Authors

Binghe Xu¹, Huiping Li², Zefei Jiang³, Lin Gu⁴, Jinhai Tang⁵, Hui Xie⁵, Yueyin Pan⁶, Yunjiang Liu⁷, Shude Cui⁸, Xiaojia Wang⁹, Li Cai¹⁰, Yiqiong Zhang¹¹, Huadong Zhao¹², Zhimin Shao¹³

Affiliations

¹ Department of Medical Oncology, National Cancer Center/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100021, China.
² Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Department of Breast Oncology, Peking University Cancer Hospital & Institute, Beijing 100142, China.
³ Department of Breast Cancer, the Fifth Medical Center of Chinese PLA General Hospital, Beijing 100071, China.
⁴ Department of Breast Cancer, Tianjin Cancer Institute and Hospital, Tianjin 300060, China.
⁵ Department of Breast Cancer, Jiangsu Provincial Hospital, Nanjing 210029, China.
⁶ Department of Breast Cancer, the First Affiliated Hospital of China University of Science and Technology, Hefei 230001, China.
⁷ Department of Breast Cancer, the Fourth Hospital of Hebei Medical University, Shijiazhuang 050011, China.
⁸ Department of Breast Cancer, Henan Cancer Hospital, Zhengzhou 450008, China.
⁹ Department of Breast Cancer, Zhejiang Cancer Hospital, Hangzhou 310012, China.
¹⁰ Department of Breast Cancer, Harbin Medical University Cancer Hospital, Harbin 150081, China.
¹¹ Department of Clinical Development, Pfizer (China) R&D Co. Ltd, Shanghai 201203, China.
¹² Department of Statistics, Pfizer (China) R&D Co. Ltd, Shanghai 201203, China.
¹³ Department of Breast Surgery, Shanghai Cancer Center/Cancer Institute, Shanghai Medical College, Fudan University, Shanghai 200032, China.

PMID: 36714346
PMCID: PMC9829502
DOI: 10.21147/j.issn.1000-9604.2022.06.07

Abstract

Objective: This post-approval safety study assessed the efficacy and safety of exemestane after 2-3 years of tamoxifen treatment among postmenopausal women with estrogen receptor-positive (ER+) early breast cancer in China.

Methods: Enrolled patients had received 2-3 years of tamoxifen and were then switched to exemestane for completion of 5 consecutive years of adjuvant endocrine therapy. The primary endpoint was the time from enrollment to the first occurrence of locoregional/distant recurrence of the primary breast cancer, appearance of a second primary or contralateral breast cancer, or death due to any cause. Other endpoints included the proportion of patients experiencing each event, incidence rate per annum, relationships between human epidermal growth factor receptor 2 status and time to event, and relationship between disease history variables and time to event.

Results: Overall, 558 patients were included in the full analysis set: 397 (71.1%) completed the study, 20 experienced an event, and 141 discontinued [47 owing to an adverse event (AE); 37 no longer willing to participate]. Median duration of treatment was 29.5 (range, 0.1-57.7) months. Median time to event was not reached. Event-free survival probability at 36 months was 91.4% (95% CI, 87.7%-95.1%). The event incidence over the total exposure time of exemestane therapy was 3.5 events/100 person-years (20/565). Multivariate analysis showed an association between tumor, lymph node, and metastasis stage at initial diagnosis and time to event [hazard ratio: 1.532 (95% CI, 1.129-2.080); P=0.006]. Most AEs were grade 1 or 2 in severity, with arthralgia (7.7%) being the most common treatment-related AE.

Conclusions: This study supports the efficacy and safety of exemestane in postmenopausal Chinese women with ER+ breast cancer previously treated with adjuvant tamoxifen for 2-3 years. No new safety signals were identified in the Chinese population.

Keywords: Chinese; early breast cancer; estrogen receptor-positive; exemestane; postmenopausal women; tamoxifen.