A Study to Evaluate the Safety and Effectiveness of Trastuzumab Emtansine (T-DM1) as Therapy in Chinese Participants With HER2 Positive Advanced Breast Cancer

An Observational Study to Evaluate the Safety and Effectiveness of Trastuzumab Emtansine (T-DM1) as Second- or Later-Line Therapy in Chinese Patients With HER2 Positive Advanced Breast Cancer

This study is a post-marketing, observational, multicenter, prospective study. It will investigate the the safety and effectiveness of T-DM1 in the Chinese population in real-world clinical practice.

Inclusion Criteria:

• Diagnosed with HER2-positive, unresectable locally advanced or metastatic breast cancer before the start of T-DM1 treatment
• Had prior treatment for breast cancer which must contain a taxane and trastuzumab
• Get the treatment of T-DM1 for the first time after diagnosis of breast cancer

Exclusion Criteria:

• Patients not receiving treatment for HER2-positive breast cancer with T-DM1 according to standard of care and in line with the current summary of product characteristics (SPC)/local labeling
• Has been previously treated with T-DM1 before current clinical visit
• Currently participating in any clinical trials
• Previously participated in any clinical trials investigating anti-HER2 drug within 1 year of the initiation of T-DM1