A Study to Assess Treatment Patterns and Treatment Adherence in Early HER2-positive Breast Cancer Participants After Treatment Decentralization

Inclusion Criteria: * Diagnosis of stage II and III HER2+ eBC according to European Society For Medical Oncology (ESMO) guidelines * Underwent curative-intent surgical resection for BC * Histologically documented HER2-positive BC (determined per American Society of Clinical Oncology \[ASCO\]/College of American Pathologists \[CAP\] guidelines) before or after surgery Exclusion Criteria: * Any medical or psychiatric condition that, in the investigator's opinion, would compromise the participant's ability to provide informed consent or to complete study-related questionnaires * Receipt of prior neoadjuvant or adjuvant therapy for HER2+ BC at a center other than the 10 participating study sites (Bor, Kladovo, Institute for oncology and Radiology of Serbia (IORS), Loznica, Pančevo, Požarevac, Smederevo, Smederevska Palanka, Šabac, Valjevo) * Participants administratively belonging to the following secondary centers: Bor, Kladovo, Loznica, Pančevo, Požarevac, Smederevo, Smederevska Palanka, Šabac, or Valjevo, who initiated neoadjuvant therapy at IORS instead of their local secondary center