18F-fluorodeoxyglucose (FDG) PET/CT after two cycles of neoadjuvant therapy may predict response in HER2-negative, but not in HER2-positive breast cancer

Abstract

The aim of this prospective study was to assess the ability of 18F-fluorodeoxyglucose (18FDG) positron emission tomography/computed tomography (PET/CT) scanning to predict pathological complete response (pCR) in breast cancer, and to investigate whether timing of the scan and trastuzumab treatment influence the accuracy of pCR prediction in human epidermal growth factor receptor 2 (HER2) positive breast cancer patients. We treated 81 locally advanced breast cancer patients with four cycles of neoadjuvant chemotherapy (NAC). HER2-negative breast cancer patients received NAC alone, while HER2-positive breast cancer patients received NAC plus trastuzumab. 18FDG PET/CT scans were scheduled at baseline and after the second cycle of NAC. Axillary lymph node (ALN) dissection was performed after the last cycle of neoadjuvant therapy. Relative changes in standardized uptake values (SUV) between the two PET/CT scans (ΔSUV) in primary tumors and ALN metastases were calculated. There were 75 patients with 150 PET/CT scans in the final analysis, including 41 HER2-negative and 34 HER2-positive cases. In the HER2-negative group, the ΔSUV predicted overall and ALN pCR; the receiver operating characteristics-areas under curve (ROC-AUC) were 0.87 and 0.80 (P = 0.0014 and 0.031, respectively) and the negative predictive values were 94% and 89% respectively. However, in the HER2-positive group, ΔSUV could predict neither overall nor ALN pCR; the ROC-AUCs were only 0.56 and 0.53, with P = 0.53 and 0.84, respectively. Hence, the ΔSUV after two cycles of neoadjuvant therapy could predict pCR in HER2-negative patients treated with NAC alone, but not in HER2-positive patients treated with NAC plus trastuzumab.

Complete Metabolic Response on Interim 18F-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography to Predict Long-Term Survival in Patients with Breast Cancer Undergoing Neoadjuvant Chemotherapy

“…In aggressive tumor subtypes (TNBC or HER2+), our findings on the prognostic role of PET parameter confirm and extend on previous reports. Despite contradicting results, the ability of SUV reduction to predict pCR and survival has been investigated in TNBC and HER2+ tumors. However, limited information is available on the relationship between survival and residual FDG uptake during or following NAC in these subtypes.…”

The Value of 18F-FDG PET/CT Imaging Combined With Pretherapeutic Ki67 for Early Prediction of Pathologic Response After Neoadjuvant Chemotherapy in Locally Advanced Breast Cancer

“…In addition, it was well addressed that metabolic changes during therapy in PET/CT are highly dependent on tumor subtype. 31 , 32 We extended the research by exploring the predictive value of Ki67 and ΔSUVmax% in different subtypes, but there were no patients reached pCR in primary tumor in Luminal A (0/4) and TNBC (0/9) subtypes. Thus, we analyzed ΔSUVmax% in Luminal B and Her2 overexpress subtypes and found ΔSUVmax% could predict pCR for Luminal B patients but not for Her2 overexpress ones.…”

[18F]FDG and [18F]FLT PET for the evaluation of response to neo-adjuvant chemotherapy in a model of triple negative breast cancer

“…Recent studies report that TNBC tumors usually have higher metabolic activity than those of other phenotypes, being aggressive and [ 18 F]FDG avid [ 39 ]. Indeed, [ 18 F]FDG uptake has been largely used to efficiently distinguish TNBC patients responsive to different NAC therapies, compared to other subtypes such as HER-2 positive tumors [ 40 , 41 , 42 ]. The nature of PET images (i.e., low spatial resolution, high statistical uncertainty noise, and ill-defined margins) renders the MTV and TLG/TLP quantification particularly hard.…”

“…Many studies apply ROC curves to define an optimal threshold value of radiotracers uptake, able to discriminate responders [ 14 , 36 , 41 , 42 ]. The differences in the published threshold value are caused by several factors, which have to be taken into account, such as the definition of good pCR, the time of PET, or the chemotherapy regimen.…”