Clinical outcomes comparison of 10 years versus 5 years of adjuvant endocrine therapy in patients with early breast cancer

• Main Authors: Li Li, Bingmei Chang, Xiaoyue Jiang, Xueke Fan, Yingrui Li, Teng Li, Shanshan Wu, Jun Zhang, Seyed Kariminia, Qin Li
• Format: Article
• Language: English
• Published: BMC 2018-10-01
• Series: BMC Cancer
• Subjects: Breast cancer; Extended endocrine treatment; Tamoxifen; Aromatase inhibitor; Disease-free survival
• Online Access: http://link.springer.com/article/10.1186/s12885-018-4878-4
• ISSN: 1471-2407

Abstract Background Adjuvant endocrine therapy undoubtedly prolongs the time to recurrence for patients with hormone-positive early breast cancer. Extended endocrine therapy to 10 years or longer has been expected to bring a greater clinical advantage. However, the related research conclusions are controversial. Methods Tamoxifen (TAM), Aromatase Inhibitor (AI), Exemestane, letrozole (LET) and anastrozole were used as key words in the literature search. After the patients completed 5 years of adjuvant endocrine treatment, they were allocated to continue endocrine treatment for 5 years or receive placebo/observation for 5 years. Disease-free survival (DFS) and overall survival (OS) were the end points. Systematic assessment was performed using Stata 12.0. Results Twelve trials including 30,848 cases were involved. The overall analysis demonstrated that extended endocrine therapy to 10 years significantly prolonged DFS compared with 5 years of endocrine therapy [hazard ratio (HR) = 0.84, 95% CI: 0.73–0.97]. Subgroup analysis showed that DFS was significant prolonged with TAM 5y - AI 5y treatment versus TAM 5y treatment and with (AI and/or TAM) 5y - LET 5y treatment versus (AI and/or TAM) 5y treatment [(HR = 0.61, 95% CI: 0.50–0.76) and (HR = 0.81, 95% CI: 0.71–0.93), respectively]. However, no significant difference was found in the DFS with TAM 5y - TAM 5y treatment versus TAM 5y treatment (HR = 0.97, 95% CI: 0.81–1.17). Overall and subgroup analysis did not demonstrate an OS benefit of therapy extended to 10 years. A DFS benefit of extended endocrine therapy to 10 years was verified in the lymph node-positive subgroup, postmenopausal subgroup and ER+ and/or PR+ subgroup (HR = 058, 95% CI: 0.45–0.75; HR = 0.70, 95% CI: 0.58–0.80; HR = 0.80, 95% CI: 0.67–0.96). Conclusions An extended 10 years of endocrine treatment yields a DFS benefit for patients with early breast cancer; (AI and/or TAM) 5y - AI 5y treatment is the optimal choice. ER+ and/or PR+, postmenopausal and lymph node-positive patients are the most suitable groups.