Relevant factors for the optimal duration of extended endocrine therapy in early breast cancer.

Abstract

PURPOSE:

For postmenopausal patients with hormone receptor-positive early breast cancer, the optimal subgroup and duration of extended endocrine therapy is not clear yet. The aim of this study using the IDEAL patient cohort was to identify a subgroup for which longer (5 years) extended therapy is beneficial over shorter (2.5 years) extended endocrine therapy.

METHODS:

In the IDEAL trial, 1824 patients who completed 5 years of adjuvant endocrine therapy (either 5 years of tamoxifen (12%), 5 years of an AI (29%), or a sequential strategy of both (59%)) were randomized between either 2.5 or 5 years of extended letrozole. For each prior therapy subgroup, the value of longer therapy was assessed for both node-negative and node-positive patients using Kaplan Meier and Cox regression survival analyses.

RESULTS:

In node-positive patients, there was a significant benefit of 5 years (over 2.5 years) of extended therapy (disease-free survival (DFS) HR 0.67, p = 0.03, 95% CI 0.47-0.96). This effect was only observed in patients who were treated initially with a sequential scheme (DFS HR 0.60, p = 0.03, 95% CI 0.38-0.95). In all other subgroups, there was no significant benefit of longer extended therapy. Similar results were found in patients who were randomized for their initial adjuvant therapy in the TEAM trial (DFS HR 0.37, p = 0.07, 95% CI 0.13-1.06), although this additional analysis was underpowered for definite conclusions.

CONCLUSIONS:

This study suggests that node-positive patients could benefit from longer extended endocrine therapy, although this effect appears isolated to patients treated with sequential endocrine therapy during the first 5 years and needs validation and long-term follow-up.

• Authors: Erik J Blok, Judith R Kroep, Elma Meershoek-Klein Kranenbarg, Marjolijn Duijm-de Carpentier, Hein Putter, Gerrit-Jan Liefers, Johan W R Nortier, Emiel J Th Rutgers, Caroline M Seynaeve, Cornelis J H van de Velde, IDEAL Study Group
• Journal: Breast cancer research and treatment (Breast Cancer Res Treat) Vol. 168 Issue 2 Pg. 413-420 (Apr 2018) ISSN: 1573-7217 [Electronic] Netherlands
• PMID: 29230665 (Publication Type: Clinical Trial, Phase III, Comparative Study, Journal Article, Randomized Controlled Trial)

Chemical References

• Antineoplastic Agents, Hormonal
• Aromatase Inhibitors
• Receptors, Estrogen

Topics

• Aged
• Antineoplastic Agents, Hormonal (therapeutic use)
• Aromatase Inhibitors (therapeutic use)
• Breast Neoplasms (drug therapy, mortality, pathology)
• Chemotherapy, Adjuvant (methods)
• Disease-Free Survival
• Female
• Follow-Up Studies
• Humans
• Kaplan-Meier Estimate
• Lymphatic Metastasis (pathology)
• Middle Aged
• Netherlands (epidemiology)
• Postmenopause
• Receptors, Estrogen (metabolism)
• Time Factors