ERBB2 and breast cancer: However, pre-menopausal patients were more likely to have HER2-positive CTCs than post-menopausal patients (chi-squared test, χ2 = 4.8, p = 0.028), and patients with ductal or lobular invasive breast cancer were less likely to have HER2-positive CTCs than patients with other histological types of BC (chi-squared test, χ2 = 6.08, p = 0.048).