In addition, serum zonulin levels were significantly lower in the control group (2.19 ng/mL ± 1.45) than in the other two groups of BC patients: HR+HER2- (5.41 ng/mL ± 4.16, p < 0.01) and HR+HER2+ (6.06 ng/mL ± 4.30, p < 0.01) (Figure 10b). Here, ERBB2 is linked to breast cancer.