Randomised controlled trials of lapatinib (alone, in combination with, or following other therapies) in women with breast cancer were eligible for inclusion. Trials that compared different doses of lapatinib were excluded.
The outcomes of interest were overall survival, progression-free survival, mortality, time to disease progression, objective response rate, clinical benefit rate, and toxicity.
The included trials were all of lapatinib taken with another treatment (capecitabine, paclitaxel, or letrozole) compared with the other treatment alone or the other treatment plus placebo. Included eligible patients had locally advanced or metastatic HER2-positive breast cancer. Two trials were of first-line treatment, and one trial was of patients who had progressed after treatment with anthracycline, taxane, and trastuzumab.
Two reviewers independently selected studies, with disagreements resolved by consensus, or by a third reviewer.