TUMOR-CELL PROLIFERATION AND SURVIVAL IN PATIENTS WITH PROSTATE-CANCER FOLLOWED EXPECTANTLY

Purpose: Prostate cancers have different biological potentials, and ag gressive tumors are difficult to identify when still localized. Tumor cell proliferation determined by MIB-1 expression has been suggested a s an important predictor for outcome in several human cancers includin g the prostate. We test the possible prognostic value of tumor cellula r proliferation in prostate cancer patients treated with no intent to cure. Materials and Methods: Formalin fixed, paraffin embedded tumor t issue obtained at the time of diagnosis from 221 patients originating from a well known complete Danish prostate cancer population was immun ohistochemically investigated. The tumor cell proliferation rate was d etermined using the MIB-1 antibody. Tumors were clinically localized i n 57% of the patients. Results: Tumor cell proliferation rate expresse d by the MIB-1 score significantly correlated with tumor stage (p < 0. 001) and malignancy grade (p < 0.001). The MIB-1 score, divided into l ow and high by the median value, showed significant association with d isease specific survival in the entire study population (p < 0.0001), as well as in the 125 patients suffering from clinically localized dis ease (p = 0.018). Multivariate analyses showed that MIB-1 was a signif icant (p = 0.0003) prognostic factor in the entire population, includi ng advanced disease stages. However, in the theoretically curable clin ically localized subpopulation MIB-1 was not significant (p = 0.08) co ntrary to histopathological grade (p = 0.02), erythrocyte sedimentatio n rate (p = 0.02) and T classification (p = 0.035). Conclusions: Prost ate tumor cell proliferation, expressed by MIB-1 immunoreactivity, dem onstrated significant association with disease specific survival. Howe ver, MIB-1 is a close alternative to histopathological grade in descri bing the natural history of clinically localized prostate cancer. The additional prognostic value and the practical consequence of tumor cel l proliferation remain to be clarified.