Independent prognostic significance of cell cycle regulator proteins p16INK4a and pRb in advanced-stage ovarian carcinoma including optimally debulked patients: a translational research subprotocol of a randomised study of the Arbeitsgemeinschaft Gynaekologische Onkologie Ovarian Cancer Study Group

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Abstract
The purpose of the study is to test the hypothesis that expression of cell cycle regulatory proteins p16INK4a and pRb is significantly associated with prognosis in ovarian carcinomas. We performed immunohistochemical analysis of p16INK4a and pRb expression and correlated with survival in a series of 300 patients with FIGO stage IIb-IV ovarian carcinoma which were enrolled in a randomized prospective trial evaluating two different platinum and paxlitaxel chemotherapy combinations after radical surgery. p16INK4a negative tumours (17/300; 6%) had a significantly worse prognosis (univariate analysis, PP=0.009). Among p16INK4a-positive tumours (283 out of 300; 94%), survival was better for patients with intermediate expression as compared to low or high expression levels (P=0.001). High expression levels of pRb were associated with an incremental deterioration of prognosis (univariate analysis, P=0.004; multivariate analysis: odds ratio 2.98, P=0.002). This observation held also true in the subgroup of optimally debulked patients (n=82), in whom the most important established prognostic factor, postoperative residual tumour cannot be applied. In conclusion p16INK4a and pRb are independent prognostic factors in advanced-stage ovarian carcinomas after radical surgery and postoperative chemotherapy. High pRb expression is a significant prognosticator in optimally debulked patients and may hold potential for subgroup stratification in postoperative treatment.