['Clinical variables with more accuracy to predict biologically insignificant prostate cancer are needed. We evaluated the combination of transrectal ultrasound-guided biopsy of the prostate (TRUSBx) pathologic and radiologic findings in their ability to predict the biologic potential of each prostate cancer.', 'A total of 1043 consecutive patients who underwent TRUSBx were reviewed. Using pathologic criteria, patients with prostate cancer (n = 529) and those treated with radical prostatectomy (RP) (n = 147) were grouped as: "insignificant" (Gleason score ≤ 6, prostate-specific antigen (PSA) density ≤ 0.15 ng/ml, tumor in ≤ 50% of any single core, and < 33% positive cores) and "significant" prostate cancer. TRUSBx imaging and pathology results were compared with the RP specimen to identify factors predictive of "insignificant" prostate cancer.', 'TRUSBx pathology results demonstrated perineural invasion in 36.4% of "significant" versus 5.4% of "insignificant" prostate cancers (p < 0.01) and pathologic invasion of periprostatic tissue in 7% of significant versus 0% of insignificant prostate cancers (p < 0.01). TRUS findings concerning for neoplasia were associated with significant tumors (p < 0.01). Multivariable analysis demonstrated perineural invasion in the biopsy specimen (p = 0.03), PSA density (p = 0.02) and maximum tumor volume of any core (p = 0.02) were independently predictive of a significant prostate cancer.'] Are perineural invasion and TRUS findings complementary in predicting prostate cancer biology?