Identifying the window of aggressive postpartum breast cancer based on the 21-gene Oncotype DX® test in women with HR+, HER2-negative breast cancer
6 affiliations
- 1Division of Hematology-Oncology, Department of Medicine, University of California, Los Angeles
- 2David Geffen School of Medicine, University of California, Los Angeles
- 3College of Letters and Science, University of California, Los Angeles
- 4Medical Affairs, Abbott
- 5Clinical Biostatistics, Abbott
- 6Department of Surgery, University of California, Los Angeles
Abstract
Postpartum breast cancer (PPBC) is associated with worse outcomes in young women with breast cancer and demonstrates distinct transcriptomic features, yet a temporal definition based on gene expression has not been established. We conducted a single-institution retrospective cohort study to evaluate the impact of postpartum status on the 21-gene Oncotype DX Recurrence Score® (RS) in hormone receptor-positive, HER2-negative young women with breast cancer. Among 385 patients, 153 were nulliparous, 62 were more than 10 years postpartum, and 170 were within 10 years postpartum. Diagnosis within one year of childbirth was associated with a 13.2-point higher RS compared with nulliparous patients (p < 0.001). Defining PPBC as within 3 years postpartum was associated with increased odds of RS category shift (OR 2.83, p = 0.001). In the context of contemporary adjuvant treatment, with patients diagnosed within three years postpartum more likely to receive chemotherapy, ovarian function suppression, and CDK4/6 inhibitors, differences in IDFS associated with time since last childbirth did not result in significantly worse IDFS within the follow-up period (89.0% in patients with PPBC up to 3 years vs. 93.7% in all other patients p = 0.39). These findings indicate that tumors diagnosed within the first year postpartum have significantly elevated RS, and that the period of most aggressive PPBC, as reflected by gene expression profiles, may arise in the more recently postpartum period, in the first 0–3 years postpartum.
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BibTeX
@article{zhang2026identifying,
title = {{Identifying the window of aggressive postpartum breast cancer based on the 21-gene Oncotype DX® test in women with HR+, HER2-negative breast cancer}},
author = {Shiliang Zhang and Katelyn J. Queen and Niharika Duggirala and Eric Yang and Marla Lipsyc-Sharf and Jennifer Racz and John Bennett and Kaden Hong and Yashila Suresh and Charlotte Hamilton and Meghana Pitta and Nicole Chien and Emily La and Christy A. Russell and Aditya Bardia and Nimmi S. Kapoor},
journal = {npj Breast Cancer},
year = {2026},
month = jul,
doi = {10.1038/s41523-026-01002-2},
url = {https://doi.org/10.1038/s41523-026-01002-2},
note = {CC BY},
}
RIS
TY - JOUR
TI - Identifying the window of aggressive postpartum breast cancer based on the 21-gene Oncotype DX® test in women with HR+, HER2-negative breast cancer
AU - Shiliang Zhang
AU - Katelyn J. Queen
AU - Niharika Duggirala
AU - Eric Yang
AU - Marla Lipsyc-Sharf
AU - Jennifer Racz
AU - John Bennett
AU - Kaden Hong
AU - Yashila Suresh
AU - Charlotte Hamilton
AU - Meghana Pitta
AU - Nicole Chien
AU - Emily La
AU - Christy A. Russell
AU - Aditya Bardia
AU - Nimmi S. Kapoor
PY - 2026
DA - 2026/07/01
JO - npj Breast Cancer
DO - 10.1038/s41523-026-01002-2
UR - https://doi.org/10.1038/s41523-026-01002-2
AB - Postpartum breast cancer (PPBC) is associated with worse outcomes in young women with breast cancer and demonstrates distinct transcriptomic features, yet a temporal definition based on gene expression has not been established. We conducted a single-institution retrospective cohort study to evaluate the impact of postpartum status on the 21-gene Oncotype DX Recurrence Score® (RS) in hormone receptor-positive, HER2-negative young women with breast cancer. Among 385 patients, 153 were nulliparous, 62 were more than 10 years postpartum, and 170 were within 10 years postpartum. Diagnosis within one year of childbirth was associated with a 13.2-point higher RS compared with nulliparous patients (p < 0.001). Defining PPBC as within 3 years postpartum was associated with increased odds of RS category shift (OR 2.83, p = 0.001). In the context of contemporary adjuvant treatment, with patients diagnosed within three years postpartum more likely to receive chemotherapy, ovarian function suppression, and CDK4/6 inhibitors, differences in IDFS associated with time since last childbirth did not result in significantly worse IDFS within the follow-up period (89.0% in patients with PPBC up to 3 years vs. 93.7% in all other patients p = 0.39). These findings indicate that tumors diagnosed within the first year postpartum have significantly elevated RS, and that the period of most aggressive PPBC, as reflected by gene expression profiles, may arise in the more recently postpartum period, in the first 0–3 years postpartum.
SN - 2374-4677
ER -