...Age will be assessed in years = neratinib initiation date - date of birth`Description of age`Gender will be described in percentage of Male and Female among patients`Description of Gender`BMI will be assessed in kg/m2`Description of BMI`Menopausal status will be described in percentage of Premenopausal, Perimenopausal, Postmenopausal, Surgical/other reason for amenorrhea`Menopausal status`Comorbidities will be described in number and percentage of patients with at least one relevant comorbidity`Comorbidities`HER2 overexpression/amplification testing will be assessed by Immunohistochemistry (IHC), Fluorescence in situ hybridization (FISH), Chromogenic in situ hybridization (CISH)`HER2 overexpression/amplification testing`Hormone receptor status will be described in percentage of patients with Estrogen receptor (ER) positive, Progesterone receptor (PR) positive, ER and PR negative`Hormone receptor status`Primary tumor location will be described in percentage of patients with Left Breast cancer, Right Breast cancer`Primary tumor location`Primary tumor histology will be described in percentage of patients with Infiltrating ductal carcinoma, Infiltrating lobular carcinoma, Invasive carcinoma, Tubular, Other`Primary tumor histology`Histological grade will be described in percentage of patients with G1 Well differentiated, G2 Moderately differentiated, G3 Poorly differentiated, G4 Undifferentiated`Histological grade`Pathologic stage (AJCC classification) of Breast Cancer will be described in percentage of patients with stages 1, 2A, 2B, 3A, 3B, 3C`Pathologic stage (AJCC classification) of Breast Cancer...