Cancer volume of lymph node metastasis predicts progression in prostate cancer

Clinical outcome is variable in prostate cancer patients with regional lymp h node metastasis. We studied 269 patients who had regional lymph node meta stasis at the time of radical retropubic prostatectomy and bilateral pelvic lymphadenectomy at the Mayo Clinic between January 1987 and December 1992. Two hundred fifty-three (94%) patients received androgen deprivation thera py within 90 days of radical prostatectomy. Patients ranged in age from 47 to 79 years (median, 67 years). Median follow-up was 6.1 years (range, 0.3- 10.5 years). Nodal cancer volume (size) was measured by the grid-counting m ethod. Cox proportional hazards models were used to determine the impact of numerous clinical and pathologic findings on systemic progression-free sur vival. Systemic progression was defined as the presence of distant metastas is documented by biopsies or radiographic examinations (abdominal computeri zed tomography, plain radiographs, or bone scan). Five-year progression-fre e survival was 90%. In predicting systemic progression using Cox multivaria te analysis, only nodal cancer volume added significantly to the model cont aining the primary cancer variables (Gleason score, cancer volume, and DNA ploidy). The relative hazard rate for a doubling in nodal cancer volume was 1.6 (95% confidence interval, 1.3 to 2.0; p < 0.0001). Spearman rank analy sis showed a correlation between nodal cancer volume and Gleason score of t he primary cancer, the number of positive nodes, the aggregate length of me tastases, and the largest nodal cancer diameter (correlation efficient = 0. 37, 0.63, 0.96, and 0.95, respectively). Our data indicate that nodal cance r volume was the most significant nodal determinant of progression to dista nt metastasis in lymph nodepositive prostate cancer patients. We recommend that the diameter of the largest metastasis be evaluated in patients with m etastases, because this is a more powerful predictor of patient outcome tha n current methods, which recommend mere counting of the number of positive nodes.