Interobserver Variation in the Assessment of Immunohistochemistry Expression Levels in HER2-Negative Breast Cancer: Can We Improve the Identification of Low Levels of HER2 Expression by Adjusting the Criteria? An International Interobserver Study.

The classification of human epidermal growth factor receptor 2 (HER2) expression is optimized to detect HER2-amplified breast cancer (BC). However, novel HER2-targeting agents are also effective for BCs with low levels of HER2. This raises the question whether the current guidelines for HER2 testing are sufficiently reproducible to identify HER2-low BC. The aim of this multicenter international study was to assess the interobserver agreement of specific HER2 immunohistochemistry scores in cases with negative HER2 results (0, 1+, or 2+/in situ hybridization negative) according to the current American Society of Clinical Oncology/College of American Pathologists (ASCO/CAP) guidelines. Furthermore, we evaluated whether the agreement improved by redefining immunohistochemistry (IHC) scoring criteria or by adding fluorescent in situ hybridization (FISH). We conducted a 2-round study of 105 nonamplified BCs. During the first assessment, 16 pathologists used the latest version of the ASCO/CAP guidelines. After a consensus meeting, the same pathologists scored the same digital slides using modified IHC scoring criteria based on the 2007 ASCO/CAP guidelines, and an extra "ultralow" category was added. Overall, the interobserver agreement was limited (4.7% of cases with 100% agreement) in the first round, but this was improved by clustering IHC categories. In the second round, the highest reproducibility was observed when comparing IHC 0 with the ultralow/1+/2+ grouped cluster (74.3% of cases with 100% agreement). The FISH results were not statistically different between HER2-0 and HER2-low cases, regardless of the IHC criteria used. In conclusion, our study suggests that the modified 2007 ASCO/CAP criteria were more reproducible in distinguishing HER2-0 from HER2-low cases than the 2018 ASCO/CAP criteria. However, the reproducibility was still moderate, which was not improved by adding FISH. This could lead to a suboptimal selection of patients eligible for novel HER2-targeting agents. If the threshold between HER2 IHC 0 and 1+ is to be clinically actionable, there is a need for clearer, more reproducible IHC definitions, training, and/or development of more accurate methods to detect this subtle difference in protein expression levels.

Treatment of early-stage breast cancer with percutaneous thermal ablation, an open-label randomised phase 2 screening trial: rationale and design of the THERMAC trial.

INTRODUCTION: Breast cancer is the most frequently diagnosed malignancy worldwide but almost half of the patients have an excellent prognosis with a 5-year survival rate of 98%-99%. These patients could potentially be treated with thermal ablation to avoid surgical excision, reduce treatment-related morbidity and increase patients' quality of life without jeopardising treatment effectiveness. Previous studies showed highest complete ablation rates for radiofrequency, microwave and cryoablation. However, due to heterogeneity among studies, it is unknown which of these three techniques should be selected for a phase 3 comparative study. METHODS AND ANALYSIS: The aim of this phase 2 screening trial is to determine the efficacy rate of radiofrequency, microwave and cryoablation with the intention to select one treatment for further testing in a phase 3 trial. Additionally, exploratory data are obtained for the phase 3 trial. The design is a multicentre open-label randomised phase 2 screening trial. Patients with unifocal, invasive breast cancer with a maximum diameter of 2 cm without lymph node or distant metastases are included. Triple negative, Bloom-Richardson grade 3 tumours and patients with an indication for neoadjuvant chemotherapy will be excluded. Included patients will be allocated to receive one of the three thermal ablation techniques. Three months later surgical excision will be performed to determine the efficacy of thermal ablation. Treatment efficacy in terms of complete ablation rate will be assessed with CK 8/18 and H&E staining. Secondary outcomes include feasibility of the techniques in an outpatient setting, accuracy of MRI for complete ablation, patient satisfaction, adverse events, side effects, cosmetic outcome, system usability and immune response. ETHICS AND DISSEMINATION: This study protocol was approved by Medical Research Ethics Committee of the Erasmus Medical Center, Rotterdam, the Netherlands. Study results will be submitted for publication in peer-reviewed journals. TRIAL REGISTRATION NUMBER: NL9205 (www.trialregister.nl); Pre-results.

Patient reported cosmetic outcome after vacuum assisted excision of benign breast lesions: a cross-sectional study.

OBJECTIVE: Better cosmetic outcome after vacuum assisted excision (VAE) compared to surgical excision of benign breast lesions is suggested in previous studies but has never been evaluated with validated outcome measures. In this study, patient reported cosmetic outcome after VAE was evaluated. METHODS: Patients who underwent VAE between July 2017 and December 2018 were invited to complete the cosmetic subscale of the Dutch Breast Cancer Treatment Outcome Scale, comparing the treated with the untreated breast. Response mode ranged from 1 (no difference) to 4 (large difference) and cosmetic outcome was calculated as the unweighted mean. Clinical outcomes included: tumor size, number of cores, complications, residual lesions and recurrences. RESULTS: Response rate was 73.4% (47 of 64 patients). Median tumor size was 15 mm (range 5-51 mm) and median number of cores 6.5 (range 1-85), complete excision was confirmed in all but two patients. Mean cosmetic outcome was good (mean score ≤1.75) in 74% of patients and no patients reported a poor cosmetic outcome (mean score >3.25). A hematoma occurred in five patients (one needed aspiration) and a skin rash in one patient, no patients developed an infection or seroma. CONCLUSION: In this study VAE is safe and effective for tumors up to 5 cm and patient reported cosmetic outcome was good. Patients with benign lesions could benefit from VAE as an alternative for surgical excision. ADVANCES IN KNOWLEDGE: A formal quantitative measurement of cosmetic outcome after vacuum assisted excision for benign breast lesions was still lacking. This study shows that this cosmetic outcome is overall good in benign lesions up to 5 cm.