OSTEOPONTIN AND P53 EXPRESSION ARE ASSOCIATED WITH TUMOR PROGRESSION IN A CASE OF SYNCHRONOUS, BILATERAL, INVASIVE MAMMARY CARCINOMAS

Objective.-To examine the association between expression of osteoponti n (OPN), p53, other molecular markers (Ki-67, c-erb B2, and estrogen r eceptor protein) and tumor progression in a case of synchronous, bilat eral, invasive mammary carcinomas of the same histology. Design.-Immun ohistochemistry was performed on formalin-fixed, paraffin-embedded tis sue sections. Plasma OPN level was determined by a quantitative antige n capture assay. Setting.-The patient was seen, treated, and followed up for a period of 5 years at the London Regional Cancer Centre, Ontar io, Canada. Patient.-A 60-year-old woman presented with bilateral infi ltrating mammary carcinomas of the same histologic type and grade. Bil ateral mastectomy and axillary node dissection showed involvement of 3 of 12 right axillary and 0 of 11 left axillary lymph nodes. She later developed a right chest wall recurrence, followed by widespread metas tatic disease to the skull, liver, and left femur Results.-The primary tumor of the right breast was OPN-and p53-positive, whereas the tumor of the left breast was negative for both markers. The development of right axillary lymph node metastases, chest wall recurrence, and dista nt metastases was associated in all instances with an immunohistochemi cal profile of high level expression of OPN and p53. Plasma assay for OPN at the time of last admission showed a markedly elevated OPN level . Conclusions.-lncreased p53 expression was found to be associated wit h increased tumor aggressiveness, The association of increased OPN exp ression with increased malignancy in breast cancer is a novel finding and raises the possibility of a role for OPN in tumor progression, as well as the potential for this marker in predicting clinical aggressiv eness.