The evolution of adjuvant endocrine therapy: developments since St Gallen 2005

Area of Science:

• Oncology
• Endocrinology
• Clinical Trials

Background:

• Tamoxifen is a cornerstone adjuvant endocrine therapy for breast cancer.
• Aromatase inhibitors (AIs) are increasingly used, particularly in postmenopausal women.
• Optimal duration and sequencing of endocrine therapies remain areas of active research.

Purpose of the Study:

• To review the efficacy and safety of tamoxifen and aromatase inhibitors in adjuvant endocrine therapy for breast cancer.
• To evaluate the benefits of extended adjuvant therapy and sequential AI use.
• To identify outstanding questions in breast cancer endocrine treatment.

Main Methods:

• Analysis of the Oxford Overview data.
• Review of current clinical trial evidence.
• Synthesis of findings on treatment efficacy, recurrence reduction, and side effect profiles.

Main Results:

• Tamoxifen provides sustained adjuvant benefit for at least 15 years.
• Aromatase inhibitors offer a marginal reduction in recurrence for postmenopausal women, with no clear survival advantage.
• Extended adjuvant AI therapy after 5 years of tamoxifen provides additional protection for high-risk patients.
• No significant differences in cardiovascular side effects between tamoxifen and AIs were observed.

Conclusions:

• Tamoxifen remains a highly effective adjuvant endocrine therapy.
• Aromatase inhibitors provide incremental benefits in recurrence reduction, especially in extended adjuvant settings for high-risk cancers.
• Further research is needed on optimal endocrine therapy duration, ovarian suppression, and patient selection for de-escalated treatment strategies.