We examined the concordance of Gleason scores in prostate needle biopsy specimens and the corresponding radical retropubic prostatectomy specimens in a cohort of patients grouped according to the number of cores obtained during diagnostic needle biopsy. We reviewed clinical and pathological data on a cohort of 466 men diagnosed with localized prostate cancer by needle biopsies who underwent radical retropubic prostatectomy between January 1, 1990 and July 31, 2001. Two study groups were identified, including 126 patients diagnosed with prostate cancer by extended needle biopsies (10 or more cores) and 340 diagnosed with cancer by nonextended needle biopsies (9 or fewer cores). Mean age was 60 years and median prostate specific antigen was 5.8 ng./ml. The median number of cores in the extended and nonextended biopsy groups was 12 and 6, respectively. The concordance of Gleason score in the needle biopsy and prostatectomy specimens was compared and correlated with the number of cores on needle biopsy. In the whole cohort 311 patients (67%) had identical Gleason scores on the needle biopsy and prostatectomy specimens, while 53 (11%) were over graded and 102 (22%) were under graded on needle biopsy. In patients who underwent extended needle biopsies the accuracy rate for Gleason scoring was 76% with 10% over and 14% under graded. The highest accuracy rates were in patients with 13, 14 and 16 cores (89%, 87% and 100%, respectively). No patients in the extended needle biopsy group had a discrepancy of more than 2 Gleason units in grade in the biopsy and surgical specimens. In those who underwent nonextended needle biopsies the accuracy rate for Gleason scoring was 63% with 12% over and 25% under graded. There were significantly different rates of accuracy (p = 0.008) and under grading (p = 0.01) in the 2 needle biopsy groups. Patients with a needle biopsy Gleason score of less than 7 had significantly higher concordance with the prostatectomy Gleason score when extended biopsies were done compared with nonextended biopsies (p = 0.001). Prostate cancer grading by extended needle biopsy is a better predictor of the final Gleason score than nonextended needle biopsy, as determined by radical prostatectomy histological evaluation. Therefore, extended prostate needle biopsy provides better guidance to determine the appropriate treatment in patients with prostate cancer.

We investigated the relationship between prostate volume and cancer detection by needle biopsy, and determined the effect of an increased number of cores on the sampling error of needle biopsy on large prostate glands. The study cohort included 750 consecutive patients who underwent first time transrectal ultrasound guided prostate needle biopsy from January 1995 to August 2001. Prostate volumes were divided into quartiles (13 to 34, 34.1 to 45, 45.1 to 64 and 64.1 to 244 cc). Multivariate analysis controlling for age, prostate specific antigen (PSA) and biopsy indication was performed to determine the effect of the number of cores and prostate volume on prostate cancer detection. Patients diagnosed with prostate cancer were older (p = 0.0035) and had higher PSA levels (p = 0.0002) than those with no cancer on biopsy. Decreasing cancer detection rates were seen with increasing prostate volume (p = 0.0074). The OR of detection for each additional core was 0.99 (95% CI 0.93, 1.06), suggesting that increasing the number of biopsy cores did not increase the rate of prostate cancer detection. Multivariate analysis revealed that patients with larger prostates had the same, or possibly lower, cancer detection rate as the number of biopsy cores was increased. Patients with larger prostates were older (p <0.0001), had higher PSA levels (p <0.0001) and were even more likely to have undergone biopsy for increased PSA rather than abnormal digital rectal examination alone (p <0.0001). Our study suggests that the lower cancer detection rate for men with large prostates may be due to a decrease in the use of increased serum PSA for prostate cancer detection in larger prostates in addition to other factors such as sampling error. Increased serum PSA levels in cases of larger prostates, although a risk factor for prostate cancer warranting biopsy, may also be due to nonmalignant sources such as benign prostatic hyperplasia.