Parathyroid hormone-related protein (PTHrP) has recently been identified in 60% of a series of primary breast cancers. The detection of a bone-resorbing factor in tumors with a propensity to metastasize to bone prompted study of PTHrP in breast cancer metastasis. PTHrP was localized by immunohistology in 12 of 13 (92%) breast cancer metastases in bone and in 3 of 18 (17%) metastases in non-bone sites. The statistical difference was highly significant (P < 0.0001). Production of PTHrP as a bone-resorbing agent may contribute to the ability of breast cancers to grow as bone metastases.


Supported by the Anti-Cancer Council of Victoria and the National Health and Medical Research Council of Australia.

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