It will be conducted as an international multicenter prospective observational cohort study in a population of ErbB2 positive metastatic breast cancer patients, whose disease has progressed after trastuzumab-containing regimen, comparing outcomes in two groups: Group 1: patients receiving Lapatinib-capecitabine immediately after 1st Trastuzumab progression (second line treatment), and Group 2: patients receiving Lapatinib-capecitabine after 2 or more lines of treatment after 1st trastuzumab progression (third line or greater).

Lapatinib in combination with capecitabine is a standard of care treatment for ErbB2+ metastatic breast cancer (MBC) patients who have progressed after anthracyclines, taxanes and trastuzumab treatment. Results from the lapatinib pivotal trial showed that the addition of lapatinib to capecitabine increased median time to progression (TTP) even among heavily pre-treated patients (median of 4 prior lines of therapy). A recent ad hoc subset analysis of this trial suggested that earlier administration of lapatinib-capecitabine in MBC patients who progress after trastuzumab may produce better clinical outcomes. The TYCO study was designed to evaluate if early switch to lapatinib-capecitabine in patients with ErbB2+ MBC who have progressed on trastuzumab-containing regimen improves TTP in comparison with a later start (after several lines of therapy). Secondary objectives include Overall Response Rate (ORR), 1 year Overall Survival (OS), and description of reported serious adverse events. This is an international, multicenter, prospective, observational (non-interventional) study in 269 ErbB2+MBC patients whose disease has progressed after treatment with trastuzumab. Two cohorts will be compared; Group 1: patients receiving lapatinib-capecitabine immediately after first trastuzumab progression, and Group 2: patients receiving lapatinib-capecitabine after two or more lines of treatment after first trastuzumab progression. Eligibility criteria include females aged 18 or more with confirmed ErbB2+ MBC who have progressed after a previous trastuzumab-containing regimen, eligible to start standard therapy with lapatinib-capecitabine at approved conventional doses, as per local label approval. The study duration is of 12 months with data collection at baseline and approximately every 3 months thereafter. Patient evaluations will be conducted per standard patient care in each center and TTP will be determined by the treating physician (clinically or radiologically). Enrollment started in February 2010 and completion of accrual is estimated for December 2011.

• Women with ErbB2+ MBC (ErbB2 expression confirmed by immunohistochemistry or FISH/CISH, either in the primary tumor or in the metastasis, according to the institution's common practice);
• Older than 18 years old;
• Have received prior treatment with trastuzumab-containing regimen for ErbB2+ breast cancer;
• Progressing after trastuzumab-containing regimen either used for the treatment of metastatic disease or progressing after adjuvant /neoadjuvant trastuzumab treatment;
• Eligible to start standard treatment with Lapatinib-capecitabine at conventional doses, OR receiving standard treatment with
• Lapatinib-capecitabine at conventional doses, for no longer than 10 weeks from the start of the treatment to the date of inclusion in the study;
• Signed consent to participate and release information for this study.

All cases of ErbB2 positive metastatic breast cancer, receiving approved standard treatment with lapatinib-capecitabine, after trastuzumab-containing regimen progression in community setting. Patients from private and public settings.