Parathyroid hormone related protein and skeletal morbidity in breast cancer

The presence of parathyroid hormone related protein (PTHRP) in human breast cancers has been assessed by immunohistochemistry using a polyclonal antiserum specific for the mid-region sequence 37–67 in an immunoperoxidase technique. The primary tumours from 155 normocalcaemic, consecutive women with early breast cancer who had been followed up for a minimum of 5 years were assessed. Dewaxed paraffin sections of formalin fixed tissue was used throughout. Positive PTHRP staining was detected in 56% of the cancers and was unrelated to standard prognostic factors, recurrence or survival. However, PTHRP positivity was related to the development of bone metastases ( P ≤ 0.03) and hypercalcaemic episodes. PTHRP is implicated as the humoral factor responsible for hypercalcaemia associated with breast cancer and tumour positivity may be a useful predictor of which women will develop bone metastases.