ERBB2 and neoplasm: The distribution of baseline serum ECD (bECD) values showed that levels appear to be higher in patients with HER2-positive tumours (median: 44.5 ng ml−1; 25th, 75th percentiles: 15.2, 114.3) vs HER2-negative tumours (median: 9.9 ng ml−1; 25th, 75th percentiles: 8.0, 12.4); however, bECD did not predict response.