DNA ploidy and survival of patients with clinically localized prostate cancer treated without intent to cure.

BACKGROUND The optimal approach to diagnosis and treatment of localized prostate cancer remains controversial. Deoxyribonucleic acid (DNA) ploidy has been suggested as an important predictor for outcome in prostate cancer. The purpose of this study was to correlate DNA ploidy with disease-specific survival in patients with clinically localized prostate cancer treated with no intent to cure. METHODS DNA ploidy was determined by flow cytometry in archival formalin fixed, paraffin embedded tumor tissue obtained at diagnosis in 120 patients with clinically localized prostate cancer with a nearly complete follow-up. RESULTS Ninety (75%) of the tumors were diploid, while only 11 (9%) tumors were categorized as tetraploid. Tumor DNA ploidy (diploid versus nondiploid) significantly associated with histopathological grade (P=0.002) and disease-specific survival (P=0.011), while there was no association with tumor stage (P=0.054). In a multivariate Cox analysis, histopathological grade (P=0.005) was the only significant predictor of disease-specific death, while analyzing the 96 low-grade tumors separately, DNA ploidy became significant (P= 0.024). CONCLUSIONS Flow cytometric determined nondiploidy was associated with disease-specific death in patients with clinically localized prostate cancer, but DNA ploidy provided additional prognostic information in patients with low-grade tumors only.