Methods
The electronic medical record data at the time of trastuzumab
administration were retrospectively reviewed. The following exclusion
criteria were applied to 229 breast cancer patients who received
trastuzumab at Osaka Medical and Pharmaceutical University Hospital
during the 4-year study period: missing information on human epidermal
growth factor receptor type 2 (HER2) status (n =1); missing
information on eosinophils (n =11); or use of treatments other
than trastuzumab (n =41).