Eight studies were included (n=6,564). Of these 82 per cent of patients (n=5,354) had reported HER2 status information, of which 29 per cent (n=1,536) had tumours that overexpressed HER2 protein or had amplification of the HER2 gene.
For patients with HER2-positive breast tumours (n=1,536) anthracycline-based chemotherapy was superior to non-anthracycline-based regimens with respect to the risks of relapse (pooled HR = 0.71, 95% CI: 0.61, 0.83; p<0.001) and death (pooled HR = 0.73, 95% CI: 0.62, 0.85; p<0.001)
For patients with HER2-negative breast tumours (n=3,818) there was no significant difference between those who received anthracycline-based compared with non-anthracycline-based regimens with respect to disease-free survival (HR = 1.00, 95% CI: 0.90, 1.11) and overall survival (HR = 1.03, 95% CI: 0.92, 1.16).
The test for treatment by HER2 status interaction yielded significant results for disease-free survival (p<0.001) and for overall survival (p<0.001).
Sensitivity analysis revealed that the type of HER2 assay, the proportion of patients assessed for HER2 status and the type of anthracycline had no impact upon the interaction between anthracycline use and HER2 status.
There was no evidence of publication bias based on funnel plots or Egger’s test.