Fig. 4: Risk ratio of intracranial metastatic disease with the addition of pertuzumab or lapatinib to trastuzumab for patients with HER2-positive breast cancer.

Risk ratios were calculated from the proportion of patients in each study arm who developed the intracranial metastatic disease over the study course. Studies here are stratified by disease stage: either early (stage I–II) or advanced (stage III–IV). The size of each box represents the weight of each study in the meta-analysis. The vertical solid line represents the point of equivalence between dual and single HER2 therapy. The vertical dashed and dotted lines represent the points of summary for fixed and random effects models, respectively, and the diamonds represent 95% CI for the summary relative risks. Analyses were performed with the R programming language⁵⁰ and the R package meta⁵¹.