The immunophenotypic differences between primary and metastatic tumour cells could influence patient’s treatment or/and the results of selected diagnostic procedures.
That prompted us to investigate potential differences between primary tumours and corresponding synchronous lymph node metastases in the T  1/N+/M0 breast cancer patients. The investigated group consisted of 108 patients with invasive ductal breast cancer, who underwent radical surgery. The expression of ER, PR, HER2 as well as CK5/6, P-cadherin, EGFR and Ep-CAM was assessed immunohistochemically.
Our data suggest that ER, PR, HER2, EGFR and CK5/6 are expressed conservatively, with some minor changes between primary tumour and simultaneous lymph node metastases. On the contrary, Ep-CAM and P-cadherin immunoreactivity in primary and metastatic cells varied significantly. This variation might exclude Ep-CAM and P-cadherin as potential diagnostic or therapeutic targets.