BONE SIALOPROTEIN EXPRESSION IN PRIMARY HUMAN BREAST-CANCER IS ASSOCIATED WITH BONE METASTASES DEVELOPMENT

Breast cancer metastasizes to bone more frequently than to any other o rgan, and over 80% of advanced breast cancer patients develop bane met astases, Our recent demonstration that human breast cancer cells expre ss bone sialoprotein (BSP), a bone matrix protein, provides a possible clue for the selective affinity of breast cancer cells for bone, We t ested the hypothesis that detection of BSP in primary human breast can cer could be a potential indicator of the ability of breast cancer cel ls to metastasize to bone, BSP expression was evaluated in the primary breast cancers of 39 patients using immunoperoxidase and two specific anti-BSP antibodies, None of these patients presented clinically or s cintigraphically detectable bone metastases at the time of surgery, In the course of their disease, 22 patients developed clinically diagnos ed bone metastases, Expression of BSP in breast cancer cells from pati ents who developed bone metastases nas significantly higher (p = 0.008 , according to the Mann-Whitney test) than in patients with no bone in volvement, No association was found between BSP expression in the prim ary breast lesions and axillary lymph node metastases, BSP expression was significantly increased in infiltrating ductal carcinoma compared with infiltrating lobular carcinoma (p = 0.0023), No correlation,vas f ound between immunoreactivity to BSP antibodies and estrogen receptor (ER) status, progesterone receptor (PR) status, or age, Our data sugge st that BSP could help to identify which women will develop bone metas tases and provide new bases for the understanding of the molecular mec hanism(s) responsible for breast cancer cells osteotropism.