Expression of cell-cycle regulator p27 is correlated to the prognosis and ER expression in breast carcinoma patients.

Cell cycle inhibitor p27 is variously expressed in breast carcinoma. A possible association between the expression of p27 and the prognosis of breast carcinoma remains to be elucidated. We investigated the expression of p27 and cyclin D1 in a retrospective series of 216 breast carcinomas immunohistochemically. Expression of p27 (p27 LI) ranged from 0 to 93.6% (median 62.4%). There was a positive association between p27 LI and cyclin D1 (p < 0.01) and between p27 LI and ER (p < 0.0001). In the combination study of p27 LI and cyclin D1 expression, the patients classified as low p27 LI/cyclin D1 negative had a poorer prognosis than those in other categories. p27 was identified as an independent prognostic factor by the multivariate Cox proportional hazard model with a relative risk of death of disease of 4.1 (p < 0.05; vs. high p27 LI compared to the median). Assessment of p27 expression and examination of both p27 LI and cyclin D1 expression may identify breast carcinoma patients who would benefit from adjuvant therapy.