ERBB2 and neoplasm: Wulfing et al (2006) discovered that 50% of patients had evidence of HER-2-positive cells in the blood and that this correlated with survival. It can be noted that some patients who were initially judged to have HER-2-negative tumours had HER-2-positive CTCs. It can be noted that some patients who were initially judged to have HER-2 negative tumours had HER-2 positive CTCs. A study of 456 primary patients showed that 28% had ⩾1 CTC in 3 × 7.5ml of blood but the presence of CTCs did not correlate with any prognostic features of the primary tumour (Rack et al, 2006).