Parathyroid hormone-related protein expression, in combination with nodal status, predicts bone metastasis and prognosis of breast cancer patients.

Parathyroid hormone-related protein (PTHrP) has been known to play an important role in the formation of meta-static lesions in the bone. However, there remains controversy over its practical role in predicting the occurrence of bone metastasis and the prognosis of breast cancer patients. In this study, we attempted to investigate the clinical value of PTHrP expression status in the primary lesions of breast cancer patients. We immunohistochemically investigated PTHrP expression in surgically resected specimens from 125 primary breast cancer patients whose clinicopathological background and long-term prognosis were available. Positive PTHrP staining was demonstrated in 79 (63.2%) tumors. PTHrP was expressed significantly more frequently in the tumors of premenopausal patients. Bone metastases were significantly more common in patients with T4 tumors, with a positive node, with distant metastasis and with PTHrP-positive tumors. Multivariate logistic analysis revealed positive PTHrP expression as an independent risk factor for predicting bone metastasis. PTHrP expression was significantly related to a shorter overall survival. Bone metastasis was found significantly more frequently (28.3%) in PTHrP- and node-positive cases than in double-negative cases, and the rate was more pronounced in postmenopausal cases (32.1%). Expression of PTHrP in primary lesions, in combination with positive nodal status, is indicative of an increased risk of bone metastasis in breast cancer patients.