This non-interventional prospective study will assess the safety of Herceptin SC (subcutaneous administration) as used in routine clinical practice. Patients with HER2-positive early breast cancer, naive and non-naive of HER2+ treatment who are to be treated in the neoadjuvant and adjuvant setting and scheduled to initiate a treatment with Herceptin SC in routine clinical practice use are eligible to participate. The total study duration is anticipated to be 38 months.

Inclusion Criteria:

• Aged >/= 18 years
• Patients with HER2-positive early breast cancer who according to national guidelines are eligible for neoadjuvant or adjuvant HER2+ treatment
• Patients for whom the investigator has decided to start a treatment with Herceptin SC
• Trastuzumab treatment naive or non-naive (previously intravenous treatment)
• Informed consent

Exclusion Criteria:

• Patients previously treated with Herceptin SC treatment

Patients with HER2-positive early breast cancer scheduled to initiate a treatment with Herceptin SC.