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Purpose: Breast cancer progression varies across molecular subtypes, and treatment options for human epidermal growth factor receptor 2 (HER2)-low expression tumors are limited compared with those of HER2 overexpression tumors. Comprehensive information regarding the epidemiology and clinical outcomes of metastatic HER2-low expression breast cancer in a Southeast Asian population is lacking., Methods: This retrospective cohort study was performed to analyze data from patients with de novo advanced breast cancer, including HER2 expression, tumor stage, and metastatic pattern. Statistical analyses, including chi-square tests and survival analyses, were used to compare HER2-low expression and HER2-negative groups., Results: Of the 491 patients, 21.2% had HER2-low expression, 30% had HER2 overexpression, and 50% had HER2-negative expression. Among the hormone receptor (HR)-positive patients, 34% had HER2-low expression; in the triple-negative patients, the HER2-low incidence was 20.6%. No significant differences in clinical characteristics between HER2-low and HER2-negative groups were observed, except for more HR-positive patients in the HER2-low group. HER2-low patients had a longer overall survival (OS) than HER2-negative patients (43 v 23 months; hazard ratio, 0.7; P < .001), especially in HR-positive patients. After adjusting for HR status, HER2-low patients maintained improved outcomes. HR-positive HER2-low patients showed nonsignificant OS gains compared with HR-positive HER2-negative patients, regardless of first-line chemotherapy or endocrine therapy., Conclusion: This study revealed the incidence and clinical outcomes of HER2-low expression in de novo advanced breast cancer, suggesting favorable outcomes, particularly in HR-positive breast cancer. These findings may inform personalized treatment strategies. Further research into the mechanisms and implications of HER2-low expression in breast cancer is required.

Background: The breast cancer treatment paradigm has shifted to neoadjuvant treatment. There are many advantages to neoadjuvant treatment, such as tumor downsizing, in vivo tumor biology testing, treating micrometastasis, and achieving complete pathological response (a surrogate marker for overall survival). However, in the post neoadjuvant settings, sentinel lymph node biopsy can be done using a dual staining technique to decrease the false-negative rate (FNR) and increase the detection rate. However, many hospitals are not equipped to use radioisotopes. Here we investigate the detection rate and accuracy of sentinel lymph node biopsy in post neoadjuvant treatment breast cancer, comparing radioisotope, isosulfan blue, and indocyanine green (ICG) approaches., Material and Methods: This prospective study includes breast cancer patients (T2-4, N1-2) who had received neoadjuvant treatment. Carcinomas were confirmed by tissue pathology. Patients who had previous surgical biopsy or surgery involving the axillary regions, and those with a history of allergy to ICG, isosulfan blue, or radioisotope were excluded from the study., Result: The study was done between July 1, 2019 to March 31, 2020. The mean age of participants was 53 years. Fourteen (60.87%) were post-menopause, two (8.7%) were perimenopause, and seven (30.43%) were premenopause. The clinical-stage distribution of the participants was: 2A (8.7%), 2B (34.78%), 3A (43.48%), and 3B (13.04%). The primary tumor size was 4.82 ± 2.73 cm. The lymph node size was 1.8 ± 0.96 cm. The detection rates at the individual level were 95.23% with ICG, 85.71% with isosulfan blue, and 85.71% with a radioisotope. The detection rate increased up to 100% when the ICG and blue dye methods were combined. The FNRs of sentinel lymph node biopsy at the individual level were: 10% using ICG, 30% using isosulfan blue, and 40% using radioisotope. At the lymph node level, the detection rates were 93.22% using ICG, 81.78% using isosulfan blue, and 53.87% using a radioisotope. The FNRs of sentinel lymph node biopsy at the lymph node level were 19.05% with ICG, 21.43% with isosulfan blue, and 18.03% with a radioisotope. However, the FNR was less than 10% when ICG, isosulfan blue, and a radioisotope were combined., Conclusion: We can perform sentinel lymph node biopsy by combining blue dye with ICG as an optional modality and achieve a comparable outcome with combine radioisotope in locally advanced breast cancer after neoadjuvant treatment., Competing Interests: All authors have no any financial and personal relationships with other people or organization that could inappropriately influence (bias) their work., (© 2020 The Authors.)

Background: Plasma cell neoplasms (PCNs) presenting with masses are not common. Variable morphology, expression of CD56 and cyclin D1, and Epstein-Barr virus (EBV)-encoded small RNA (EBER) status have been described with a promising diagnostic role. There is no data of these findings in Thai patients., Objective: To study morphology, CD56 and cyclin D1 expression and EBER status in PCNs presenting with masses., Material and Method: Thirty-nine mass-forming PCNs with available materials between 2006 and 2010 were identified from Siriraj Hospital pathology database. H&E slides were reviewed for morphologic grade according to Bartl grading system. Immunohistochemistryfor CD56 and cyclin D1 and EBER in situ hybridization were analyzed on tissue microarray sections of the included cases., Results: Of 39 cases, it comprised 31 (79.5%) plasma cell myelomas (PCMs), five (12.8%) osseous plasmacytomas (OPs), and three (7.7%) extramedullary plasmacytomas (EMPs). Intermediate-grade morphology was common to all types of PCNs. CD56 and cyclin D1 positivity were more often in PCMs comparing with OPs and EMPs; however differences in expression of these markers among different types of PCNs were insignificant (p > 0.05). An EBER-positive EMP was identified., Conclusion: The majority of mass-forming plasma cell tumors in the studied population are PCM-related. Intermediate-grade morphology is common in all types of PCNs. A value of CD56 and cyclin D1 immunostains in discrimination between types of PCNs cannot be confirmed in the current study. Identification of the EBER-positive EMP suggests that EBV association in plasma cell tumor can be encountered in Thais.