ERBB2 and neoplasm: Levels were also found to be elevated in patients with human epidermal growth factor receptor 2 (HER2) negative (mean = 48.22, median = 21.46, range = 0–400.52 LEVs/ml, n = 37) compared to HER2 positive (mean = 15.13, median = 11.34, range = 7.41–46.41 LEVs/ml; p = 0.026, n = 7) tumor status (Fig. 4b).