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Sequential tamoxifen and AI for 5 years versus an AI for 5 years
Source: Breast Cancer Treatment (PDQ®)–Health Professional Version, National Cancer Institute.
Source updated: April 25, 2025 · Captured 2026-09-09.
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The evidence indicates that there is no benefit to the sequential use of tamoxifen and an AI for 5 years over 5 years of an AI.
Evidence (sequential tamoxifen and AI vs. an AI for 5 years):
A large, randomized trial of 9,779 patients compared DFS of postmenopausal women with hormone receptor–positive breast cancer between initial treatment with sequential tamoxifen for 2.5 to 3 years followed by exemestane for a total of 5 years versus exemestane alone for 5 years. The primary end points were DFS at 2.75 years and 5.0 years.[70][Level of evidence B1]
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A large, randomized trial of 9,779 patients compared DFS of postmenopausal women with hormone receptor–positive breast cancer between initial treatment with sequential tamoxifen for 2.5 to 3 years followed by exemestane for a total of 5 years versus exemestane alone for 5 years. The primary end points were DFS at 2.75 years and 5.0 years.[70][Level of evidence B1]
The 5-year DFS rate was 85% in the sequential group and 86% in the exemestane-alone group (HR, 0.97; 95% CI, 0.88–1.08; P = .60).
Similarly in the IBCSG 1-98 trial (NCT00004205), two sequential arms were compared with 5 years of letrozole.[71][Level of evidence B1]
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Similarly in the IBCSG 1-98 trial (NCT00004205), two sequential arms were compared with 5 years of letrozole.[71][Level of evidence B1]
There was no difference in DFS when the two sequential arms were compared with 5 years of letrozole (letrozole to tamoxifen HR, 1.06; 95% CI, 0.91–1.23; P = .45 and tamoxifen to letrozole HR, 1.07; 95% CI, 0.92–1.25; P = .36).
The FATA-GIM3 trial (NCT00541086), which was not included in the meta-analysis, compared 2 years of tamoxifen followed by 3 years of one of the three AIs with 5 years of an AI.[72]
The FATA-GIM3 trial (NCT00541086), which was not included in the meta-analysis, compared 2 years of tamoxifen followed by 3 years of one of the three AIs with 5 years of an AI.[72]
No significant difference in the 5-year DFS rate was found between the two approaches (88.5% for switching; 89.8% for upfront AI; HR, 0.89; 95% CI, 0.73–1.08; P = .23).
In a meta-analysis, which included 12,779 patients from the trials, the 7-year recurrence rate was slightly reduced from 14.5% to 13.8% in the groups that received 5 years of an AI (RR, 0.90; 95% CI, 0.81–0.99; P = .045). The overall mortality rate at 7 years was 9.3% in the tamoxifen-followed-by-AI groups and 8.2% in the AI-alone groups (RR, 0.89; 95% CI, 0.78–1.03; P = .11).[60][Level of evidence A2]
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