Diagnostic accuracy of FDG-PET-CT to predict axillary lymph node response after neoadjuvant chemotherapy in lymph nodepositive breast cancer patients - Research Open Access

Sep 23, 2026

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Fluorodeoxyglucose positron emission tomography combined with CT (FDG-PET-CT) is sometimes used to evaluate response to neoadjuvant chemotherapy (NAC) in lymph node-positive breast cancer, guiding extent of surgery and radiotherapy. This study retrospectively assessed diagnostic accuracy for predicting axillary response after NAC, using postoperative histopathology as the reference standard. Across 75 women, sensitivity for detecting residual axillary metastases was low, while specificity remained high, yielding limited negative predictive performance.

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CategoryHealthcare

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Rajan et al. Breast Cancer Research (2026) 28:46 Breast Cancer Research [https://doi.org/10.1186/s13058-026-02223-w](https://doi.org/10.1186/s13058-026-02223-w) RESEARCH Open Access Diagnostic accuracy of FDG-PET-CT to predict axillary lymph node response after neoadjuvant chemotherapy in lymph nodepositive breast cancer patients Kiran Kasper Rajan1,5*, Joni J. Nijveldt 1,2, Jasper H. G. Helthuis3, Ellen M. A. Roeloffzen4, Brian Vendel3, Ingrid M. Nijholt5, Miranda van’t Veer-ten Kate5, Jose van der Starre6, Wim van der Steeg7, Schelto Kruijff2,8, Martinus A. Beek 1 and Anne Brecht Francken1 Abstract Background In certain cases, some institutions use fluorodeoxyglucose positron emission tomography combined with CT (FDG-PET-CT) scans to assess response to neo-adjuvant chemotherapy (NAC) in lymph node-positive breast cancer (cN+), to determine the extent of surgery and subsequently radiotherapy. In this study, we assessed the diagnostic accuracy of FDG-PET-CT to determine the axillary response to NAC using the histopathology results as the golden standard. Methods Between 2016 and 2022, all women with cN+ breast cancer receiving NAC and axillary surgery were retrospectively identified. Patients who underwent pre-and post-NAC staging with FDG-PET-CT were included. Excluded were patients with previous ipsilateral breast cancer, occult breast cancer or bilateral breast cancer. The histopathology lymph node results from surgery were used to calculate the diagnostic accuracy of FDG-PET-CT for detecting axillary lymph node metastases post-NAC. Results Seventy-five patients were included. Forty-one patients (55%) had histologically proven axillary metastatic disease at the response evaluation after NAC, although FDG-PET positivity was only apparent in nine of these patients. There was a sensitivity of 22%(95% CI 11–38%) for FDG-PET-CT in detecting axillary lymph node metastases after NAC and a specificity of 94%(95% CI 80–99%) . The positive predictive value was 82%(95% CI 48–98%) and the negative predictive value (NPV) was 50%(95% CI 37–63%) . Conclusions FDG-PET-CT scans have a low sensitivity and NPV to identify residual disease after NAC, indicating that these scans are unlikely to aid in decision making. Omission of post-NAC FDG-PET-CT should be considered in lymph node response evaluation unless other clinical indications with no other alternative. Keywords Breast cancer, Axillary lymph nodes, Radiotherapy, FDG-PET-CT scan, Diagnostic accuracy *Correspondence: Kiran Kasper Rajan[k.k.rajan@isala.nl](k.k.rajan@isala.nl) Full list of author information is available at the end of the article © The Author(s) 2026. Open Access This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which permits any non-commercial use, sharing, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if you modified the licensed material. You do not have permission under this licence to share adapted material derived from this article or parts of it. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit [http://creati](http://creati)[vecommons.org/licenses/by-nc-nd/4.0/](vecommons.org/licenses/by-nc-nd/4.0/.)[.](vecommons.org/licenses/by-nc-nd/4.0/.) Background Worldwide, breast cancer is the most commonly diagnosed malignancy in women [1]. The mainstay of treatment is surgery with adjuvant therapy including chemo, hormonal and radiotherapy

FAQs

What does the study evaluate regarding FDG-PET-CT after neoadjuvant chemotherapy?

It evaluates how accurately FDG-PET-CT predicts axillary lymph node response after NAC in lymph node-positive breast cancer patients, using postoperative histopathology as the reference standard.

How were patients selected and what was excluded?

Women with clinically node-positive (cN+) breast cancer receiving NAC and axillary surgery were retrospectively identified between 2016 and 2022. Patients with previous ipsilateral breast cancer, occult breast cancer, or bilateral breast cancer were excluded.

What were the key diagnostic performance results?

Sensitivity was low (22%), specificity was high (94%), the positive predictive value was 82%, and the negative predictive value was 50% for detecting axillary lymph node metastases after NAC.

Sep 23, 2026

Uploaded by Aria