Interpretation of bilateral positive biopsies in prostate cancer.

Abstract

When 6 systematic prostate needle core biopsies are positive for cancer bilaterally, prediction of clinical cancer volume is limited by the unpredictable presence of contralateral incidental tumors. Criteria were sought to improve prediction. Core cancer lengths were summed unilaterally (3 biopsies) and bilaterally (6) in 65 patients with bilateral positive cores. Of the patients 31 had true bilateral cancer spread and 34 had unilateral disease with contralateral incidental tumors. For both groups correlation with prostatectomy cancer volume (r = 0.65, p < 0.001) was the same for the sum of 3 ipsilateral cores as for all 6 cores. Core cancer length sum of 3 ipsilateral biopsies predicts the largest prostatectomy cancer volume as well as the bilateral sum. Contralateral biopsies do not contribute to prediction nor distinguish bilateral spread from contralateral incidental cancers.