Limiting systemic endocrine overtreatment in postmenopausal breast cancer patients with an ultralow classification of the 70-gene signature

M Opdam, V van der Noort, M Kleijn, A Glas, I Mandjes, S Kleiterp, F S Hilbers, D T Kruger, A D Bins, P C de Jong, P P J B M Schiphorst, T van Dalen, B Flameling, R C Rietbroek, A Beeker, S M van den Heiligenberg, S D Bakker, A N M Wymenga, I M Oving, R M BijlsmaP J van Diest, J B Vermorken, H van Tinteren, S C Linn

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PURPOSE: Guidelines recommend endocrine treatment for estrogen receptor-positive (ER+) breast cancers for up to 10 years. Earlier data suggest that the 70-gene signature (MammaPrint) has potential to select patients that have an excellent survival without chemotherapy and limited or no tamoxifen treatment. The aim was to validate the 70-gene signature ultralow-risk classification for endocrine therapy decision making.

METHODS: In the IKA trial, postmenopausal patients with non-metastatic breast cancer had been randomized between no or limited adjuvant tamoxifen treatment without receiving chemotherapy. For this secondary analysis, FFPE tumor material was obtained of ER+HER2- patients with 0-3 positive lymph nodes and tested for the 70-gene signature. Distant recurrence-free interval (DRFI) long-term follow-up data were collected. Kaplan-Meier curves were used to estimate DRFI, stratified by lymph node status, for the three predefined 70-gene signature risk groups.

RESULTS: A reliable 70-gene signature could be obtained for 135 patients. Of the node-negative and node-positive patients, respectively, 20% and 13% had an ultralow-risk classification. No DRFI events were observed for node-negative patients with an ultralow-risk score in the first 10 years. The 10-year DRFI was 90% and 66% in the low-risk (but not ultralow) and high-risk classified node-negative patients, respectively.

CONCLUSION: These survival analyses indicate that the postmenopausal node-negative ER+HER2- patients with an ultralow-risk 70-gene signature score have an excellent 10-year DRFI after surgery with a median of 1 year of endocrine treatment. This is in line with published results of the STO-3-randomized clinical trial and supports the concept that it is possible to reduce the duration of endocrine treatment in selected patients.

Original languageEnglish
Pages (from-to)265-278
Number of pages14
JournalBreast Cancer Research and Treatment
Issue number2
Early online date19 May 2022
Publication statusPublished - Jul 2022


  • Antineoplastic Agents, Hormonal/therapeutic use
  • Breast Neoplasms/drug therapy
  • Chemotherapy, Adjuvant
  • Early breast cancer
  • Endocrine treatment
  • Female
  • Humans
  • MammaPrint 70-gene signature
  • Overtreatment
  • Postmenopausal
  • Postmenopause
  • Prognosis
  • Tamoxifen/therapeutic use


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