Abstract
BACKGROUND: Evaluating biomarkers, such as estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor-2 (HER2), in pathological specimens is crucial for guiding breast cancer treatment. Since biomarker expression may differ between primary and metastatic lesions, biopsy of metastatic sites is recommended whenever feasible. The liver is a common metastatic site for breast cancer, and percutaneous biopsy has traditionally been the standard approach. Recently, endoscopic ultrasound-guided tissue acquisition (EUS-TA) has emerged as an alternative method for sampling focal liver lesions. However, the utility of EUS-TA in assessing breast cancer biomarkers remains unclear. AIM: To evaluate the diagnostic performance of EUS-TA, including its ability to assess biomarkers in liver metastases from breast cancer. METHODS: This single-center, retrospective observational study included patients who underwent EUS-TA for breast cancer liver metastases between 2016 and 2023. Clinical characteristics and specimen adequacy were analyzed. A pathologist classified the obtained tissue samples into four categories: (A) insufficient for diagnosis, (B) diagnosis possible only at the cytology level, (C) histological evaluation possible, but additional immunostaining for biomarkers not feasible, and (D) histological evaluation and additional immunostaining for biomarkers feasible. RESULTS: Fifteen cases were included, with a median patient age of 68 years (all female). The median liver lesion size was 20 mm (range: 8-50 mm). The lesions were located in the left lobe in 12 cases and the right lobe in 3 cases. A 22G needle was used in 14 cases, while a 25G needle was used in 1 case. Specimen adequacy was classified as follows: category A in 1 case (6.6%), B in 2 cases (13.3%), C in 0 cases (0%), and D in 12 cases (80%). Biomarker evaluation was feasible in the majority of cases. No procedure-related adverse events were observed. CONCLUSION: EUS-TA is a valuable method for obtaining tissue samples from breast cancer liver metastases, enabling biomarker assessment in most cases.