ERBB2 and neoplasm: Although the average HER2 positivity rate among patients with MBC was higher than for EBC for all time periods and showed variations across the reporting period (22.6, 25.1, 21.3, and 21.6 % for the first, second, third, and fourth 12-month periods, respectively), these rates were also similar to those reported in the literature [2–6, 25, 26], suggesting that MBC is associated with a higher HER2 positivity rate than EBC and reflecting a more aggressive tumor cohort.