We measured OPN in plasma by ELISA , and in tumors by immunohistochemistry , in @ ( @ % ) and @ ( @ % ) , respectively , of @ postmenopausal women with hormone responsive early breast cancer treated by surgery followed by adjuvant treatment with tamoxifen + / - octreotide in a randomized trial ( NCIC CTG MA @ ; National Cancer Institute of Canada Clinical Trials Group Mammary @ ) .