Clinical implications of p57 KIP2 expression in breast cancer.

Objective: To study the relationship between expression of p57KIP2 and prognosis and other clinicopathological parameters in invasive breast cancers.

Methods: We assessed the expression of p57KIP2 in 89 cases of invasive breast cancer and 20 cases of normal breast tissue by immunohistochemical methods and analyzed the results with SPSS software (ver. 16.0).

Result: The positive expression rates of p57KIP2 protein in the invasive breast cancers and surrounding normal tissue were 30.3% (27/89) and 65% (13/20), respectively. Cases with no p57KIP2 expression exhibited a significantly higher post-operative distant metastasis rate than those with p57KIP2 expression (37.9% vs. 14.8%; P = 0.01). DFS analysis showed that p57KIP2-/C-erbB-2μ tumors also exhibited a significantly higher post-operative distant metastasis rate than the other groups (66.7% vs. 29.2%; P = 0.007), as did p57KIP2-/p53μ tumors (64.3% vs. 22.7%; P = 0.001). Survival analysis revealed that p57KIP2 was associated with breast cancer-specific survival overall (P = 0.045, log-rank test). Subgroup analysis demonstrated that individuals with p57KIP2-/C-erbB-2μ tumors experienced significantly worse post-operative survival than those with p57KIP2- /C-erbB-2- or other tumors (P = 0.006, log-rank test). p57KIP2-/p53μ tumors were associated with significantly worse post-operative survival than p57KIP2-/p53- or other tumors (P = 0.001, log-rank test). Cox regression analysis showed that p57KIP2 was a non-independent prognostic factor for breast cancer (P = 0.303).

Conclusions: p57KIP2 is expressed at low levels in invasive breast cancer and is associated with better overall survival rate and disease-free survival in breast cancer patients, but it was a non-independent prognostic factor for breast cancer. Thus, the connection between p57KIP2/p53 and p57KIP2/C-erbB-2 may provide biomarkers for breast cancer.