Subtype-guided 18F-FDG PET/CT in tailoring axillary surgery among node-positive breast cancer patients treated with neoadjuvant chemotherapy: A feasibility study
Authors: S. Wu, Y. Wang, J. Li, N. Zhang, M. Mo, J. Shen, J. Cheng, G. Liu
Journal: Annals of Oncology (2019)

Background: With the increased use of neoadjuvant chemotherapy (NAC), as well as increasing efficacy of systemic therapy, a substantial proportion of clinically node-positive patients may achieve a nodal pathologic complete response (pCR) with chemotherapy. Instead of axillary lymph node dissection (ALND), a novel surgical technique called targeted axillary dissection (TAD) including removal of sentinel lymph nodes (SLNs) and clip-marked node has been gaining acceptance in recent years. Logically, preoperative identification of patients with pCR or residual disease would allow for the optimization of axillary surgery for performing a TAD or proceeding to a ALND after NAC, thus sparing patients unnecessary procedures or expense. The aim of this study was to investigate the value of 18F-FDG PET/CT in tailoring axillary surgery by predicting nodal response among node-positive breast cancer patients after NAC. Methods: Breast cancer patients with biopsy-confirmed nodal metastasis were prospectively enrolled. At least one 18F-FDG PET/CT scan was performed before NAC (a second one after two cycles with baseline SUVmax in axillary lymph nodes ≥ 2.5), among whom a subset of patients had underwent TAD. All the patients ultimately underwent ALND. The accuracy was calculated by a comparison with the final pathologic results. Results: Table. Accuracy of 18F-FDG PET/CT to Predict Ax-pCR in Overall Population and Different Subtypes Overall population ER-HER2+ subtype The rest subtypes No. of patients 111 31 80 Ax-pCR rate (%) 55.9 74.2 48.8 AUC (95%CI) 0.75 (0.65-0.84) 0.55 (0.31-0.79) 0.80 (0.70-0.91) P value <0.05 0.69 <0.05 Optimum cut-off (%) 78.4 79.9 76.2 Accuracy (%) 75.7 54.8 77.5 Sensitivity (%) 79.0 56.5 84.6 Specificity (%) 71.4 50.0 70.7 PPV (%) 77.8 76.5 73.3 NPV (%) 72.9 28.6 82.9 In this study, 133 patients were enrolled. With the optimum cut-off value of ≥ 2.5 for the baseline SUVmax and ≥ 78.4% for the ΔSUVmax, 18F-FDG PET/CT scans showed a moderate predictive value of axillary (Ax-pCR) with an area under the curve (AUC) of 0.75 (95% CI: 0.65-0.84) (Table). Explorative subgroup analyses indicated little predictive value for estrogen receptor (ER)-negative, human epidermal factor receptor 2 (HER2)-positive (HER2-enriched) patients (AUC=0.55). And the application of 18F-FDG PET/CT could spare 22 patients from unnecessary TADs or supplementary ALNDs and reduce 1 of 3 false-negative cases occurring in TAD among the non-HER2-enriched patients. Conclusions: Application of the subtype-guided 18F-FDG PET/CT could accurately predict nodal response and aid in tailoring axillary surgery among node-positive breast cancer patients after NAC, which included identifying candidates appropriate for TAD or directly proceeding to ALND. This approach might help to avoid false-negative events occurring in TAD. Editorial acknowledgement: The manuscript was reviewed by Dr. William C. Wood, Division of Surgical Oncology, Department of Surgery, Emory University School of Medicine, Winship Cancer Institute, Atlanta, GA, USA. Legal entity responsible for the study: Fudan University Shanghai Cancer Center. Funding: Has not received any funding. Disclosure: All authors have declared no conflicts of interest.