Prognostic role of the recepteur d'origine nantais (RON) expression in ovarian cancer patients

Objective: The aim of the study was to investigate the potential clinical relevance of immunohistochemically assessed RON expression in a large, single institution series of primary untreated advanced ovarian cancer patients. Methods: Immunohistochemical analysis was performed by using the polyclonal rabbit anti-RON-β antibody (C-20, clone sc-322, Santa Cruz, California). Results were expressed as the total proportion of immunostained tumor cells (RON positivity), or the percentage of cells showing strong staining of RON expression (H-RON positivity). Results: In the overall series RON positive immunoreaction was observed in 103/141 cases, while H-Ron positivity was detected in 577141 (40.4%) cases. No association between RON and H-RON expression with response to first-line treatment was documented. During the follow up period, progression and death of disease were observed in 111 (78.7%) and 76 (53.9%) cases, respectively. Cases with strong H-RON expression has a shorter overall survival (median = 35 months) than cases with low RON levels (median = 59 months) (X2 = - 2.1, p value = 0.032). In multivariate analysis, only platinum resistance, and extent of residual tumor retained an independent negative prognostic role for OS, with the percentages of H-RON positively immunostained cells showing a borderline statistical significance (p value = 0.0643). The unfavourable role of elevated percentages of H-RON expression was maintained only in the subgroup of platinum resistant recurrent ovarian cancer patients (X2 = 3.89, p value = 0.048) compared to the platinum sensitive ones (X2 = 1.98, p value = 0.16). Conclusions: The assessment of RON expression deserves further attention as a parameter helpful to identify poor prognosis ovarian cancer patients potentially candidates to investigational agents. © 2008 Elsevier Inc. All rights reserved.