Purpose: Several studies have documented that increased biopsy sampling, that is 6 versus 12 biopsy cores, can detect more prostate cancer. It is unknown whether increased sampling of the prostate will detect a higher number of potentially insignificant tumors.
Materials and methods: We searched the surgical pathology files at The Johns Hopkins Hospital for patients in whom prostate needle biopsy was performed by a single urologist between April 1993 and April 2000, and subsequently underwent radical prostatectomy. Patients who underwent radical prostatectomy and had 8 core biopsies or less between March 1994 and August 1999 were also studied. Clinically significant tumors were defined as those with volume greater than 0.5 cc, Gleason score 7 or greater or nonorgan confined disease.
Results: A total of 297 patients with a mean age of 60 years (range 36 to 75) were evaluated. Group 1 consisted of 107 men with 8 core biopsies or less, including 51 with 6, and group 2 comprised 190 men with 9 cores or greater, including 145 with 12. The 2 groups were equal in regard to prostate specific antigen, age, digital rectal examination and transrectal ultrasound gland volume at biopsy. The only difference between the groups was a higher number of cores with cancer in group 2 (mean 2.8 versus 2.1, p = 0.0006). Of the patients who underwent radical prostatectomy 59.6% had Gleason score 6 or less, 26.3% 3+4, 6.7% 4+3 and 7.4% 8 to 9. There were 12.4% of patients with positive margins, 36.4% extraprostatic extension, and 5.4% seminal vesicle invasion and/or lymph node metastasis. Tumor volumes averaged 1.1 cc (range 0.01 to 10.7) and 60.9% of tumors were greater than 0.5 cc. Clinically significant tumors were seen in 77.4% of patients in group 1 and 74.6% in group 2. There was no significant difference in Gleason score, margin status, tumor volume, seminal vesicle invasion, or lymph node metastasis between groups 1 and 2, or in a subset analysis of men with 6 versus 12 core biopsies. However, patients in whom cancer was diagnosed with 9 core biopsies or greater were more likely to have organ confined disease (p = 0.02).
Conclusions: Although increased sampling of the prostate does not increase the detection of potentially insignificant tumors, it does appear to detect earlier stage cancer.