Immunohistochemical detection of parathyroid hormone related protein in the primary tumours of hypercalcaemic breast cancer patients

Recent studies in patients with breast cancer have implicated parathyroid hormone related protein (PTHrP) in the development of bone metastases and hypercalcaemia. The aim of this study was to investigate in breast cancer patients who developed hypercalcaemia, the relationship between immunohistochemically detectable PTHrP in the primary tumour with common prognostic factors and the pattern of metastatic spread. The primary tumours of 33 breast cancer patients who subsequently developed hypercalcaemia were examined for the presence of PTHrP using an immunohistochemical technique. 76% of primary tumours were found to contain PTHrP. A relationship between positive progesterone receptor status and the presence of PTHrP was observed but no association with oestrogen receptor status, nodal status, tumour size or age was discernible. All but two patients developed bone metastases. No relationship between the presence of PTHrP in the primary tumour and pattern of metastases in this group of patients was found.