Biological characteristics of breast cancer at the primary tumour and the involved lymph nodes.

Diminished oestrogen receptor (ER) expression in the involved axillary lymph nodes (ALN) in breast cancer compared with the primary tumour has been reported in previous studies. We have assessed a wider spectrum of tumour markers (ER, progesterone receptor (PgR), p53, Ki-67 and HER-2/neu) and compared extent and staining intensities at the primary tumour and the involved ALN on specimens of 22 cases with invasive ductal breast cancer. At the involved ALN, both the quantity of positive staining cells and the staining intensities for ER and PgR were decreased (p < 0.001 and p = 0.003, respectively). In contrast, the quantity of positive staining cells (p < 0.004) and the staining intensities for Ki-67 were increased. The differences for HER-2/neu and p53 staining at both sites were insignificant. The immunohistochemical staining properties of both the primary tumour and the ALN metastases showed no correlation with the number of involved ALN (p > 0.05). This study suggested that ALN metastasis might indicate a more unfavourable expression pattern of ER, PgR and Ki-67 in invasive ductal breast cancer.