Objectives: Contemporary prostate carcinoma is frequently of small volume and early stage. Subtotal gland ablation by minimally invasive therapies such as cryotherapy demands preoperative prediction of unifocal, unilateral, margin-negative, and small volume (less than 0.5 mL) cancer.
Methods: We examined matched biopsy and prostatectomy and clinical data from 393 patients at two institutions who underwent surgery in 2000 through 2003. Radical prostatectomy specimens were uniformly sectioned at 5-mm intervals and completely embedded. Numerous clinical and biopsy variables were correlated by regression analysis with unifocal, unilateral, margin-negative, and 0.5 mL or less volume cancer in the prostatectomy specimen. Odds ratios (OR) were determined.
Results: At prostatectomy, 92 (23%) had unifocal cancer, 90 (23%) had unilateral cancer, 348 (89%) had organ-confined cancer, and 106 (31%) had small volume cancer. Unilateral cancer occurred in 71% to 76% of cases of unilateral cancer in the biopsy (OR, 4.30; if 9 or more cores were sampled, OR rose to 6.83), and was predicted by unifocality in the biopsy (OR, 2.63). Unifocal cancer was predicted by unilateral (OR, 2.66) but not unifocal, cancer present in the biopsy. Negative surgical margins were predicted by unilateral (OR, 2.53; positive predictive value, 82%) cancer in the biopsy and by serum prostate specific antigen (OR, 5.33). Small volume cancer was predicted by unilateral (OR, 5.50) and unifocal (OR, 7.98) cancer in the biopsy; Gleason score greater than 7 predicted a non-small volume cancer (OR, 7.52).
Conclusions: Unilateral or unifocal cancer on biopsy are among the strongest predictors of unilateral, unifocal, and small volume prostate cancer in contemporary practice.