Three RCTs (n=2,264 patients) were included in the review. Two trials were multi-centre trials that used double blinding; one trial was an open-label trial.
Efficacy of lapatinib: The results of three RCTs showed significant benefits for the patients with HER2-positive breast cancer (n=705) after treatment with lapatinib in progression-free survival (HR 0.61, 95% CI 0.50 to 0.74), overall survival (HR 0.76, 95% CI 0.60 to 0.96), and in disease stabilisation or response (OR 2.23, 95% CI 1.57 to 3.18) compared with patients who were not treated with lapatinib. There were no significant differences between patients with HER2-negative breast cancer (n=1,559) who were treated with lapatinib and those who were not.
Toxicity of lapatinib (three RCTs; n=2,264 patients): Treatment with lapatinib was associated with a statistically significant increase in risk of serious adverse events (OR 1.64, 95% CI 1.21 to 2.23) and increase discontinuation of therapy due to toxicity (OR 2.28, 95% CI 1.04 to 4.97). The most frequently cited serious adverse events were diarrhoea, rash, arthralgia and fatigue. Sensitivity analyses showed non-significant trends towards increased serious adverse events and treatment when lapatinib was used with endocrine therapy rather than chemotherapy.