Background: Approximately 20% of invasive ductal breast malignancies are human epidermal growth factor receptor 2 (HER2)-positive. These patients receive neoadjuvant systemic therapy (NAT) including HER2-targeting therapies. Up to 65% of patients achieve a pathological complete response (pCR). These patients might not have needed surgery. However, accurate preoperative identification of a pCR remains challenging. A radiologic complete response (rCR) on MRI corresponds to a pCR in only 73% of patients. The current feasibility study investigates if HER2-targeted PET/CT-imaging using Zirconium-89 (⁸⁹Zr)-radiolabeled trastuzumab can be used for more accurate NAT response evaluation. Methods: HER2-positive breast cancer patients scheduled to undergo NAT and subsequent surgery received a ⁸⁹Zr-trastuzumab PET/CT both before (PET/CT-1) and after (PET/CT-2) NAT. Qualitative and quantitative response evaluation was performed. Results: Six patients were enrolled. All primary tumors could be identified on PET/CT-1. Four patients had a pCR and two a pathological partial response (pPR) in the primary tumor. Qualitative assessment of PET/CT resulted in an accuracy of 66.7%, compared to 83.3% of the standard-of-care MRI. Quantitative assessment showed a difference between the SUV_R on PET/CT-1 and PET/CT-2 (ΔSUV_R) in patients with a pPR and pCR of −48% and −90% (p = 0.133), respectively. The difference in tumor-to-blood ratio on PET/CT-1 and PET/CT-2 (ΔTBR) in patients with pPR and pCR was −79% and −94% (p = 0.133), respectively. Three patients had metastatic lymph nodes at diagnosis that were all identified on PET/CT-1. All three patients achieved a nodal pCR. Qualitative assessment of the lymph nodes with PET/CT resulted in an accuracy of 66.7%, compared to 50% of the MRI. Conclusions: NAT response evaluation using ⁸⁹Zr-trastuzumab PET/CT is feasible. In the current study, qualitative assessment of the PET/CT images is not superior to standard-of-care MRI. Our results suggest that quantitative assessment of ⁸⁹Zr-trastuzumab PET/CT has potential for a more accurate response evaluation of the primary tumor after NAT in HER2-positive breast cancer.

Introduction: Given increasing numbers of breast cancer survivors, there is an increased focus on quality of life and quality of care. This study aims to investigate whether clinical or patient reported outcomes are most important for perceived quality of care by breast cancer patients. Methods: Overall, 606 patients aged 18 years or older, who underwent breast cancer surgery 9-18 months ago in five hospitals in the Netherlands, were invited to complete an internet-based questionnaire. Patients were asked to judge a random selection of 24 patient profiles and choose which of 2 presented patients had received the best quality of care, using conjoint analysis. The individual relative importance (RI) for each outcome was estimated using Hierarchical Bayes Estimation, and averaged over all patients to assess which outcomes were most important. Results: Complete data were available for 350 patients (58%). Avoiding severe breast symptoms was most important for good quality of care according to patients (RI 23.22 [95% Confidence Interval (95% CI) 22.32-24.12]), followed by a 2 year longer disease free survival (18.30 [17.38-19.22]). However, the importance differed by age: younger patients (<50 years) assigned higher importance to longer disease free survival (21.99 [19.52-24.46]) than older patients (65 + years) (15.03 [13.88-16.18]). Conclusion: Avoiding severe breast symptoms rather than 2 year longer disease free survival is considered most important in our population of breast cancer patients for evaluation of quality of care. These data should thus be included in both information provision prior to treatment choices and post treatment quality of care evaluation.