ERBB2 and cancer: As Table 2 showed, there were significant differences in age (χ2=18.700, p =0.000), marital status (χ2=14.334, p =0.001), fertility history (χ2=14.021, p =0.000), tumour size (χ2=27.003, p =0.000), histology (χ2= 11.652, p =0.016), cancer stage (χ2=109.386, p =0.000), lymph node invasion (χ2=12.986, p = 0.001), and expression of HER-2 (χ2=3.948, p =0.047) between the mastectomy and non-mastectomy groups.