DNA ploidy and surgically treated prostate cancer. Important independent association with prognosis for patients with prostate carcinoma treated by radical prostatectomy

Abstract

The authors addressed the following question : Does DNA ploidy measurement provide additional unique prognostic information beyond the customary parameters of tumor stage and histologic grade for patients with prostate adenocarcinoma? They analyzed 494 patients treated by radical retropubic prostatectomy and bilateral pelvic lymphadenectomy at the Mayo Clinic from 1967 to 1981, pathologic stages B (n = 258), C (n = 145), and D1 (n = 91). Clinical follow-up was a minimum of 10 years. Nuclear DNA ploidy patterns were measured with the archival paraffin embedded specimen blocks using the Hedley technique. Univariate analysis demonstrated that DNA ploidy, Gleason score, and pathologic stage are all highly important prognostic variables, each with a log-rank P value of <0.0001 for progression and cause-specific survival. Multivariate analysis indicates that DNA ploidy, pathologic stage, and Gleason score are each independently important prognostic variables for progression and cause-specific survival. DNA ploidy is particularly useful for differentiating prognosis of patients with the common intermediate grade (Gleason 5-7) tumors, which constituted 76% of this series. For this data set, prognostic risk after radical prostatectomy is summarized by tables that take into account each of these three synergistic, independent variables. Within each Gleason score and pathologic-stage grouping, tumors with a nondiploid DNA content had roughly a 2.7-fold higher chance of disease progression or of causing cancer death than DNA diploid tumors. Cancer 1995 ;75 : 1935-43.