Ultrasound-guided four quadrant biopsy of the prostate: efficacy in the diagnosis of isoechoic cancer.

Five hundred and eighty men underwent transrectal ultrasound-guided biopsy of the prostate using the four quadrant biopsy (4QB) technique. Four hundred and three men had focal hypoechoic lesions of the peripheral gland but the other 177 men referred because of concern for the presence of cancer had no discrete sonographic lesion. Cancer was found from 4QB in only 32 of these 177 men (18.1%) compared to 158 of the 403 men (39.2%) with focal hypoechoic lesions (P < 0.001). Additional biopsy evidence of cancer was found in contralateral isoechoic (sonographically normal) quadrants in 41 men with focal hypoechoic cancerous lesions. In 17 men with hypoechoic lesions that were biopsy-benign, cancer was found in other isoechoic quadrants. There was no difference between the average Gleason scores of hypoechoic cancers and isoechoic cancers, other than when cancers were incidentally found in men with benign focal hypoechoic lesions. These had significantly lower scores (P = 0.02). Cancer yield in the 177 men without hypoechoic lesions increased as a function of prostate-specific antigen (PSA) level; 11% if PSA < 10ng/ml, 32% if > 20ng/ml. Prostatitis was the most common abnormal biopsy finding in these men. 4QB increases the yield of prostate cancer compared to simple biopsy of hypoechoic lesions and improves knowledge of local disease extent. 4QB is recommended for men with elevated PSA levels but no peripheral gland sonographic abnormality.