This is a multicenter, retrospective study to estimate the prevalence of different HER2 expression levels (HER2+, HER2-low, HER2 Ø) in approximately 200 breast cancer patients at FUSCC through the year of 2015 and 3000 breast cancer patients from about 10 medical centres in China between July 2021 and July 2022.~This study will be divided into two parts： The first part will include 200 subjects who were pathologically diagnosed with breast cancer at FUSCC between Jan 2015 and Dec 2015 (PART 1).This part will collect rescored HER2 expression level results based on the archived HER2 IHC slides and re-staining and re-scoring HER-2 IHC while relative demographic, treatment, and clinicopathologic data will be extracted from the FUSCC Breast Cancer Single Disease Database.~The second part will include 3000 patients from all sites in China who were pathologically diagnosed with breast cancer between July 2021 and July 2022 (PART 2). This part will collect re-assessed HER2 expression level results based on the archived HER2 IHC slides. The general information of patients, diagnosis, clinicopathological information were collected from medical records, Hospital Information System (HIS) and Laboratory Information Management System (LIS).~In PART 2, among 3000 patients, 270 from all participating sites except FUSCC should have enough tumor tissue for re-staining and re-scoring HER-2 IHC at FUSCC to analyse the concordance between leading site and other centers.~In PART 2, among 3000 patients, 800 HER-2 IHC samples will be selected for the validation through AI-assisted HER2 assessment system
This retrospective study aims to estimate the prevalence of different HER2 expression levels (HER2+, HER2-low, HER2 Ø) in approximately 200 breast cancer patients at FUSCC through the year of 2015 and 3000 breast cancer patients from about 10 medical centres in China between July 2021 and July 2022