p29 protein in breast cancer: relation between estrogen and progesterone receptors

An immunoradiometric assay was used to determine the presence of p29 protein in 68 breast cancer cyTOSOLS. The p29 values ranged from 0 to 1123 U/mg, with a mean value of 127 +/- 28.7 U/mg. Using a cutoff point of 20 U/mg the frequency of p29 positive tumors was about 55%. A quantitative and qualitative relation was found between p29 and estrogen receptor (ER), but not between p29 and progesterone receptor (PR). Discordance between p29 and ER status was found in 13 out of 68 tumors. Both the frequency of p29 positive tumors and the p29 values were significantly higher in postmenopausal than in premenopausal women, in a similar way to ER but different from PR. There was no difference in p29 content between primary tumor and metastasis. We did not find any relation among p29 primary tumors content and axillary lymph nodes involvement or tumor size.