Loss of p27KIP1 expression in fully-staged node-negative breast cancer: association with lack of hormone receptors in T1a/b, but not T1c infiltrative ductal carcinoma.

Overview

UNLABELLED: Nuclear expression of the cell cycle inhibitor p27(KIP1) is reduced in a variety of human malignancies, including breast cancer. Loss of nuclear p27(KIP1) during tumor progression, documented by immunohistochemistry (IHC), has been studied for its potential prognostic implication. We examined by IHC the association between nuclear p27(KIP1) expression and hormone receptor status in T1N0M0 breast cancer. PATIENTS AND METHODS: The correlation between nuclear p27(KIP1) expression and estrogen (ER) and progesterone (PR) hormone receptor status was analyzed in 122 human T1N0M0 (68 T1a/b, 54 T1c) breast cancer specimens. All patients were staged as N0 by axillary node dissection. RESULTS: A statistically significant reduction in p27(KIP1) expression was observed as tumor size increased from T1a/b (7%) to T1c (22%). The proportion of tumors with low nuclear p27(KIP1) expression was higher in the ER-negative/PR-negative group compared to the ER-positive/PR-positive group, but this difference was only statistically significant in the T1a/b subgroup (p=0.0007). CONCLUSION: Further investigations into causes of p27(KIP1) deregulation and their relationship to hormone receptor expression in T1N0M0 breast ductal carcinomas are warranted. Such studies may help identify prognostic, as well as predictive, markers of therapy resistance.