p21 (WAF1/CIP1) protein expression is associated with prolonged survival but not with p53 expression in epithelial ovarian carcinoma

OBJECTIVE: The objective of this study was to clarify the influence of p21 protein expression in ovarian cancer. p21 (WAF1 [wild-type p53 activated fragment 1]/CIP1) is a universal cyclin-dependent kinase inhibitor and can be induced as a downstream effector of the p53 tumor suppressor gene. METHODS: The expression of p21 was evaluated by immunohistochemical analysis with the monoclonal antibody WAF1 (Oncogene Science) on 106 formalin-fixed, paraffin-embedded tissue samples of epithelial ovarian cancer. RESULTS: p21 was expressed in 65 (61%) of all cases. p21 expression was associated with early stage in FIGO classification (FIGO I and II, P = 0.003) and no tumor residues after primary tumor resection (P = 0.018). Immunohistochemical staining results were judged as negative if no tumor nuclei were stained, as weak positive if 1-49% were stained, and as strong positive if over 50% of nuclei were stained. Clinical follow-up showed a better overall survival for cases with strong p21 expression (79 months) versus 40 months for weak expression and 30 months for no expression (P = 0.033). Previously determined p53 expression of this cohort was compared with p21 status. p53 overexpression was observed in 49 cases (48%) and showed no association with p21 expression. CONCLUSION: No correlation was found between p21 and p53 expression. p21 expression is a significant prognostic marker for improved survival in ovarian cancer and is associated with early FIGO stage and zero tumor residues after primary tumor resection.