The purpose of the study is to evaluate whether the time to progression for the DOXIL and docetaxel combination therapy group was superior to that of the group treated with docetaxel monotherapy in participants with advanced breast cancer.

This is a randomized (the study medication is assigned by a random order), active control (study medication will be compared with available standard care of treatment), parallel-group (each treatment group will be treated simultaneously at the same time and each participant only receives one treatment regimen as assigned), open-label (both the investigator and the participant know the intervention received by the participant), multicenter study designed to determine if women with locally advanced or metastatic breast cancer, who were previously treated with prior anthracycline therapy in the neoadjuvant (administration of treatment before surgery) or adjuvant setting (administration of treatment after surgery), and who also had a disease-free interval of at least 12 months since the end of their last cytotoxic therapy, would benefit from the addition of DOXIL to docetaxel therapy. Approximately 751 participants will be randomly assigned to either receive docetaxel monotherapy or DOXIL in combination with docetaxel therapy. Treatment is to continue until disease progression or the occurrence of unacceptable treatment related toxicity. Safety evaluations will include assessments of adverse events which will be recorded from the first study related procedure until 30 days after the last dose of medication; clinical laboratory tests and tests for cardiac function (multiple gated acquisition scan/echocardiogram and electrocardiogram) which will be monitored throughout the study.

Inclusion Criteria:

• Females with locally advanced or metastatic breast cancer who received prior anthracycline therapy in the neoadjuvant or adjuvant setting, and had at least a 12-month disease-free interval since the end of their last cytotoxic therapy, were eligible for the study
• Participants who received prior hormonal therapy, or no more than 1 cytotoxic chemotherapy regimen (anthracyclines, taxanes, or antitubulin agents were not permitted), or both for advanced disease
• Participants with normal cardiac function, as evidenced by a normal left ventricular ejection fraction

Exclusion Criteria:

• More than 1 prior cytotoxic chemotherapy regimen for advanced breast cancer
• Treatment of advanced breast cancer with an anthracycline, paclitaxel, docetaxel, vinorelbine, or vinblastine (prior treatment of advanced breast cancer with 1 regimen that included alkylating agents or antimetabolite agents was acceptable)
• Less than 2 months since the last dose of trastuzumab
• Less than 3 weeks since last dose of tamoxifen or fulvestrant, or less than 1 week since the last dose of other hormonal therapy
• Radiation to areas of disease within 30 days before study enrollment
• History of New York Heart Association Class II or greater cardiac disease or other clinical evidence of congestive heart failure